_______________________________________________________
http://www.metrokc.gov/health/apu/std/condomsefficacy.pdf

Centers for Disease Control and Prevention
Safer o Healthier o People
Prevention message for HIV, the virus that causes AIDS
Latex condoms, when used consistently and correctly, are highly
effective in preventing
the transmission of HIV, the virus that causes AIDS.
For More information, contact:
National Center for HIV, STD & TB Prevention
Office of Communications (404) 639-8890
http://www.cdc.gov/nchstp/od/nchstp.html

Latex Condoms and Sexually Transmitted Diseases

- Prevention Messages -

AIDS is, by far, the most deadly sexually transmitted disease and
considerably more scientific evidence
exists regarding condom effectiveness for prevention of HIV infection
than for prevention of other STDs.
The body of research on the effectiveness of latex condoms in
preventing sexual transmission of HIV is both
comprehensive and conclusive. In fact, the ability of latex condoms to
prevent transmission of HIV has
been scientifically established in "real life" studies of sexually
active couples as well as in laboratory
studies.
Theoretical Basis for Protection: Latex condoms cover the penis and
provide an effective barrier to
exposure from genital secretions such as semen and vaginal fluids,
blocking the pathway of sexual
transmission of HIV infection.
Laboratory Studies that determine whether or not organisms can
penetrate latex condoms under conditions
more stringent than those during intercourse demonstrate that latex
condoms provide an impermeable barrier
to viruses even smaller than HIV.
Epidemiological Studies that are conducted in real-life settings,
where one partner is infected with HIV and
the other partner is not, demonstrate conclusively that the consistent
use of latex condoms provides a high
degree of protection.
-2-
Prevention message for sexually transmitted diseases, including HIV
Latex condoms, when used consistently and correctly, are highly
effective in preventing
transmission of HIV, the virus that causes AIDS. In addition, correct
and consistent use
of latex condoms can reduce the risk of other sexually transmitted
diseases.
Prevention message for discharge diseases, other than HIV
Latex condoms, when used consistently and correctly, can reduce the
risk of
transmission of gonorrhea, chlamydia, and trichomoniasis.
Condoms can be expected to provide different levels of risk reduction
for different sexually transmitted
diseases. There is no one definitive study about condom effectiveness
for all STDs. Several studies have
demonstrated that condoms can protect against the transmission of
chlamydia, gonorrhea and
trichomoniasis, and may protect against genital herpes and syphilis.
However, because not all studies have
demonstrated protective effects, the body of evidence is considered
inconclusive. In addition, definitive data
are lacking regarding the degree of risk reduction that latex condoms
provide in preventing transmission of
chancroid and genital human papillomavirus. It is important to note
that the lack of data about the level of
condom effectiveness indicates that more research is needed - not that
latex condoms do not work. The
following includes specific information for sexually transmitted
discharge diseases, genital ulcer diseases
and human papillomavirus.
Discharge Diseases
Gonorrhea, chlamydia, and trichomoniasis are termed discharge diseases
because they are sexually
transmitted by genital secretions, such as semen or vaginal fluids.
HIV is also a discharge disease.
Theoretical Basis for Protection: As with HIV, the physical properties
of latex condoms protect against
other discharge diseases such as gonorrhea, chlamydia, and
trichomoniasis by providing a barrier to the
genital secretions that transmit STD-causing organisms.
Laboratory Studies that determine whether or not organisms can
penetrate latex condoms under conditions
more stringent than those during intercourse, demonstrate that latex
condoms provide an impermeable barrier
to organisms considerably smaller than those that cause discharge
diseases.
Epidemiological Studies that compare infection rates among condom
users and nonusers provide evidence
that latex condoms can protect against the transmission of chlamydia,
gonorrhea and trichomoniasis.
However, because some epidemiological studies show little or no
protection, the body of evidence is
considered inconclusive. Many of the studies are also inconclusive
regarding the level of protection because
of limitations in design. In general, these limitations would lead to
an underestimation of the protective
effect. More research is needed to assess the degree of protection
latex condoms provide for most discharge
diseases, other than HIV.
Prevention message for genital ulcer diseases and HPV infections
Genital ulcer diseases and HPV infections can occur in genital areas
that are covered or
protected by a latex condom. They can also occur in areas that are not
covered or
protected. Latex condoms, when used consistently and correctly, can
reduce the risk of
genital herpes, syphilis, chancroid, and HPV infection, only when the
infected areas are
covered or protected by the condom. In addition, the use of latex
condoms has been
associated with a reduction in risk of HPV-associated diseases, such
as cervical cancer.
For bibliography on condom effectiveness, contact
CDC's National Prevention Information Network
at (800) 458-5231 or www.cdcnpin.org
Genital Ulcer Diseases and Human Papillomavirus
Genital ulcer diseases include genital herpes, syphilis, and
chancroid. These diseases are transmitted
primarily through "skin-to-skin" contact from sores/ulcers or infected
skin that looks normal. HPV
infections, like genital ulcer diseases, are transmitted through
contact with infected genital skin or mucosal
surfaces/fluids. Although these infections can occur in genital areas
that are covered or protected by the
condom, they can also occur in areas that are not.
Theoretical Basis for Protection: Protection against genital ulcer
diseases and HPV depends on the site of
the sore/ulcer or infection. Latex condoms can only protect against
transmission when the ulcers or
infections are in genital areas that are covered or protected by the
condom. Thus, consistent and correct use
of latex condoms would be expected to protect against transmission of
genital ulcer diseases and HPV in
some, but not all, instances.
Laboratory Studies that determine whether or not organisms can
penetrate latex condoms under conditions
more stringent than those during intercourse, demonstrate that latex
condoms provide an impermeable barrier
to organisms considerably smaller than those that cause genital ulcer
diseases and HPV infections.
Epidemiological Studies that compare infection rates among condom
users and nonusers provide evidence
that latex condoms can protect against the transmission of syphilis
and genital herpes. However, because
some epidemiological studies show little or no protection, the body of
evidence is considered inconclusive.
Many of the studies are also inconclusive regarding the level of
protection because of limitations in design.
In general, these limitations would lead to an underestimation of the
protective effect. No conclusive studies
have specifically addressed the transmission of chancroid and condom
use.
Epidemiological studies have generally not demonstrated an association
between condom use and the risk of
HPV infection, but these studies are inconclusive because of
limitations in how they were designed. Again,
these limitations would generally lead to an underestimation of the
protective effect. Study results do,
however, show an association between condom use and risk reduction of
HPV-associated diseases, including
genital warts, cervical dysplasia and cervical cancer.

http://www.niaid.nih.gov/dmid/stds/condomreport.pdf
Workshop Summary:
Scientific Evidence on Condom Effectiveness for Sexually Transmitted
Disease (STD) Prevention
June 12-13, 2000 Hyatt Dulles Airport Herndon, Virginia
This summary report was prepared by the National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Department of
Health and Human Services.
July 20, 2001

EXECUTIVE SUMMARY
Background
Sexually transmitted diseases (STDs), including HIV, are common,
important, and preventable causes of morbidity, mortality, disability,
lost-productivity, and health care costs. In the United States, more
than 65 million individuals are living with an STD, the majority of
which are incurable viral infections. Approximately 15 million new
sexually transmitted infections occur annually in the U.S. In the
United States, approximately 493,000 individuals have died from AIDS,
and 800,000-900,000 people are living with HIV disease. Many sexually
transmitted infections can cause adverse pregnancy outcomes including
miscarriages, stillbirths, intrauterine growth restriction and
perinatal (mother-to-infant) infections. Some STDs can cause
infertility or lead to ectopic pregnancy among women and one, the
human papillomavirus, can cause cervical and anogenital cancer.
Furthermore, other STDs facilitate HIV transmission.
The Problem and the Process
Primary prevention of STD infection is an important health priority.
Unfortunately there are no STD vaccines, except for hepatitis B
vaccine, and topical microbicides to prevent STDs are not available.
Beyond mutual lifelong monogamy among uninfected couples, condom-use
is the only method for reducing the risk of HIV infection and STDs
available to sexually active individuals.
Recently, a number of Federal agencies sponsored a workshop to answer
the following question: "What is the scientific evidence on the
effectiveness of latex male condom-use to prevent STD transmission
during vaginal intercourse?" This workshop was attended by 180
persons, and the data from numerous peer-reviewed published studies
were discussed. Following the workshop, a panel of 28 experts worked
to develop this report.
The sessions included review of published information on the
properties and user patterns of the male latex condoms for vaginal
intercourse and included data from studies on pregnancy prevention.
Focused research studies have documented the high effectiveness of
condoms for prevention of pregnancy. The data associated with condom
use in eight specific STDs were considered in detail, including HIV
infection, gonorrhea, chlamydial infection (including gonococcal and
chlamydial pelvic inflammatory disease), syphilis, chancroid,
trichomoniasis, genital herpes, and genital HPV infection and
associated diseases (i.e. cervical dysplasia, cervical cancer and
genital warts).
The meeting was not intended to make public health policy
recommendations regarding the role of condoms in HIV/STD prevention
policy and programs.
Assessment of the Data
In general, the Panel found the published epidemiology literature to
be inadequate to definitively answer the question posed to the
workshop participants. Most studies reviewed did not employ a
prospective design, which is the optimal method to assess the
effectiveness of condoms in preventing infection.
i
Conclusions on STDs Transmitted by Genital Secretions
The published data documenting effectiveness of the male condom were
strongest for HIV. The Panel concluded that, based on a meta-analysis
of published studies "always" users of the male condom significantly
reduced the risk of HIV infection in men and women. These data
provided strong evidence for the effectiveness of condoms in
preventing HIV transmission in both men and women who engage in
vaginal intercourse.
The Panel also concluded that the consistency of findings across four
epidemiological studies of gonorrhea indicated that the latex male
condom could reduce the risk of gonorrhea for men.
The strongest evidence for potential effectiveness of condoms on other
STDs transmitted by genital secretions (i.e. gonorrhea in women,
chlamydial infection and trichomoniasis) was the laboratory-based
studies on the properties of the male latex condom and the strength of
the evidence for condom use reducing the risk of HIV transmission in
men and women and gonorrhea in men. The Panel concluded, however, that
because of limitations in study designs there was insufficient
evidence from the epidemiological studies on these diseases to draw
definite conclusions about the effectiveness of the latex male condom
in reducing the transmission of these diseases.
Conclusions on Genital Ulcer Diseases
The Panel agreed that the published epidemiologic data were
insufficient to draw meaningful conclusions about the effectiveness of
the latex male condom to reduce the risk of transmission of genital
ulcer diseases (genital herpes, syphilis and chancroid).
Conclusions on HPV
For HPV, the Panel concluded that there was no epidemiologic evidence
that condom use reduced the risk of HPV infection, but study results
did suggest that condom use might afford some protection in reducing
the risk of HPV-associated diseases, including warts in men and
cervical neoplasia in women.
Summary
The Panel stressed that the absence of definitive conclusions
reflected inadequacies of the evidence available and should not be
interpreted as proof of the adequacy or inadequacy of the condom to
reduce the risk of STDs other than HIV transmission in men and women
and gonorrhea in men. To definitely answer the remaining questions
about condom effectiveness for preventing STD infections will require
well-designed and ethically sound clinical studies.
ii July 20, 2001
Workshop Summary:Scientific Evidence on Condom Effectiveness for STD
Prevention
1. Introduction
Sexually transmitted diseases (STDs), including the human
immunodeficiency virus (HIV)/AIDS, are important and preventable
causes of morbidity, mortality, disability, and associated
lost-productivity and health care costs. One in five adults in the
United States has an STD (170). In the United States, approximately
450,000 individuals have died from AIDS, and 800,000-900,000 people
are living with HIV infection. Approximately 15 million new sexually
transmitted infections occur annually in the U.S. Many go undiagnosed,
and therefore untreated. The health repercussions of STDs,
particularly undiagnosed infections, can be serious. Asymptomatic
infections, which can result in unknown transmission of STDs, are
important factors in perpetuating STD/HIV infections. Many sexually
transmitted infections can cause adverse pregnancy outcomes including,
but not limited to, miscarriage, still birth, intrauterine growth
restrictions, and perinatal (mother-to-child) infections. Some STDs
are associated with infertility among women and one, the human
papillomavirus, can cause cervical cancer among women. In addition,
studies have shown that both ulcerative and non-ulcerative STDs
promote HIV transmission by augmenting HIV infectiousness and HIV
susceptibility. Multiple prospective studies have estimated this risk
to be between 2 and 5 fold (178).
STDs can be prevented. Current prevention/risk reduction strategies
include, abstinence, mutual monogamy with an uninfected partner, use
of condoms and engaging in sexual activity that does not result in the
transfer of bodily fluids or cell-to-cell transmission. There are no
marketed microbicides or vaccines (with the exception of hepatitis B
vaccine) for the prevention of STDs, although research to develop them
is underway. All STD prevention and risk reduction strategies involve
the complex interplay of biological, behavioral, social and structural
factors. These issues have been elucidated in the Institute of
Medicine report on STDs, The Hidden Epidemic (118), and the recent IOM
report on HIV prevention, No Time To Lose (144).  

2. Process: Scope of Workshop
On June 12-13, 2000, four government agencies (U.S. Agency for
International Development, Food and Drug Administration, Center for
Disease Control and Prevention, National Institutes of Health)
responsible for condom research, condom regulation, condom use
recommendations, and HIV/AIDS and STD prevention programs,
co-sponsored a workshop to evaluate the published  

1July 20, 2001
evidence establishing the effectiveness of latex male condoms in
preventing HIV/AIDS and other STDS. 1
Representatives of the sponsoring agencies and outside experts were
asked to work as a panel to review and discuss the existing literature
and write a report. The expertise of the panel members included STDs,
genitourinary tract anatomy, contraception, condoms, behavioral
science, epidemiology, medicine, and public health. This report was
developed by the panel members. The names and affiliations of the 28
panel members are listed in Appendix A.
The workshop examined only peer-reviewed literature because these
studies have been subjected to independent scientific evaluation prior
to publication. Based on literature searches and papers identified by
the speakers, discussants, meeting attendees and panel members, 138
peer-reviewed papers, published on or before June 2000, were compiled
and reviewed. From this selection, the individual presenters
determined which papers to consider based on their assessment of the
quality of the evidence contained within the papers. Presenters varied
in their criteria for inclusion or exclusion and, in general, the
Panel's deliberations were focused on the papers deemed sufficient for
inclusion by the individual presenters. Because the workshop was
structured to examine the level of protection afforded by condom use
for individual STD pathogens, presenters responsible for reviewing and
summarizing the data for each infection generally excluded studies
that presented outcomes for multiple infections in aggregate. The
reader is referred to the bibliography for a more complete view of the
issues discussed at the workshop. Additionally, for those interested
in a broader discussion, a tape recording of the two-day meeting is
available and can be ordered2. The bibliography appears in Appendix B
and includes the reviewed papers (numbered 1- 138) as well as other
papers cited in this summary (numbered 139 - 180).
The agenda for the workshop is provided in Appendix C.
1 The focus on the latex male condom for the prevention of HIV/AIDS
and STDs during penile-vaginal intercourse reflected the predominance
of the latex male condom in current condom usage, its FDA labeling for
this purpose, and the preponderance of available effectiveness
literature. The focus was not intended to diminish the need for
research on other forms of male condoms, on female condoms, and
onprevention of HIV/AIDS and STDs associated with other forms of
sexual activity, such as oral or anal intercourse. 2 Cassettes can be
obtained from:Audio Transcripts, Ltd.3660-B Wheeler Avenue,
Alexandria, VA 22304Conference #1561June 12-13, 2000 Scientific
Evidence on Condom Effectiveness and STD Prevention sponsored by
National Institute ofAllergy and Infectious Diseases

2July 20, 2001
The scientific scope of the workshop was deliberately limited to three
areas:
(1) The device. This workshop examined evidence only for the male
condoms made from natural rubber latex. According to sales data, the
latex male condom accounts for 97% of all United States condom sales
(per unit).
(2) The route of infection. The workshop addressed condom
effectiveness in preventing infections transmitted via penile-vaginal
intercourse. The U.S. Food and Drug Administration (FDA) permits
manufacturers to label latex condoms for use during penile-vaginal
intercourse as follows, "If used properly, latex condoms will help
reduce the risk of transmission of HIV infection (AIDS) and many other
sexually transmitted diseases." Other routes of infection were not
evaluated.
(3) The diseases. The workshop examined evidence related to eight
STDs: HIV infection, gonorrhea, chlamydial infection, [including
gonococcal and chlamydial pelvic inflammatory disease (PID)],
syphilis, chancroid, trichomoniasis, genital herpes caused by herpes
simplex viruses (HSV) 1 and 2, and genital human papillomavirus (HPV)
infection and HPV diseases.  

3. Evaluation Parameters

Efficacy versus Effectiveness
The protection condoms afford against STDs can be examined from three
perspectives, including:
(1) The product;
(2) The individual users, who may include those who use the device
properly, improperly or intermittently whenever they are at risk for
transmitting or becoming infected with an STD; and
(3) The population in which the prevalence of sexual behaviors,
including condom use and exposure to different STDs, may vary.
Regarding the product, protection depends on the physical properties
of the device, breakage and slippage rates, and the parts of the body
it covers. From the perspective of the individual user, protection
also depends on whether the device is used properly for every act of
intercourse or, in the parlance of condoms and STDs, whether it is
used "correctly and consistently." It is important to distinguish
between condoms' efficacy, which is the protection that the users
would receive under ideal conditions, and their effectiveness, which
is the protection they provide under actual conditions of use.
Efficacy depends primarily on the properties of the device, whereas
effectiveness depends on the  

3July 20, 2001
characteristics of the device and the user. Since multiple studies
were evaluated, study groups and their condom use behaviors varied.
The accuracy with which condom use was defined and measured also
varied from study to study. Thus, in all the studies reviewed in this
workshop, the observed relationship between reported condom use and
STDs reflects both product characteristics and user behaviors that may
fall short of ideal and also may not represent "typical" for the
population at large. For the purpose of this report, the term "condom
effectiveness" will be used to mean the level of protection against
STDs when condoms are used consistently and correctly.
Methodological Issues
To make a valid empirical assessment of condom effectiveness for STD
prevention, appropriate study design, accurate measurement, and
appropriate analyses are necessary. The panel considered the
particular methodological challenges posed by condom use studies to
determine the quality of the data and to evaluate the strength of the
evidence/conclusion. A variety of study designs were used in the
literature reviewed and they differed in their ability to provide
strong evidence of the relationship between condom use and STDs. The
ideal design, a prospective randomized controlled clinical trial, has
not been used in evaluating condom effectiveness because of ethical
concerns associated with non-use of condoms in high-risk populations.
In this design, factors that could bias results are minimized because
participants are randomly assigned to treatment and control arms. All
published studies reviewed in this document are observational studies,
that is, participants were not assigned to use or not use condoms.
Instead, the presence or occurrence of infection was compared between
those who reported using or not using condoms.
Each observational design carries its own strengths and weaknesses.
Prospective cohort studies collect information on events as they
occur. A cohort study can provide the strongest evidence among the
observational designs. To do so, this design requires following a
relatively large number of sexually active participants for an
extended period of time and can be quite costly. This design is also
vulnerable to attrition of subjects, but errors associated with recall
and selection bias can be minimized, as the cohort is assessed in real
time. It can also establish the order of events (exposure, infection,
disease).
Retrospective case-control studies or cross-sectional prevalence
studies can be relatively more economical because individuals who have
or had the disease of interest (cases) can be selected and compared
with those without the disease (controls), with data collected on
possible exposure and use of protective measures during previous
intervals. However, these studies are vulnerable to errors in recall
and selection bias. These designs also make it difficult to determine
the temporal ordering of events because exposure to infection, data on
condom use, and outcome are measured at the same time.  

4July 20, 2001
The population chosen for study, the incidence and prevalence of
disease in the population, and the numbers of subjects also have
important implications for a study's ability to detect significant
effects and to generalize these effects to other populations. In
observational studies, the ability to measure and account for
differences in risk between two groups (i.e. condom users versus
non-users) is critical. If such "confounders" are not taken into
account, the estimate of effectiveness will be biased.
Appropriate measurement of key exposures and infection or disease
outcomes is also critical. Ideally, highly specific and sensitive
diagnostic techniques for detection of infectious agents should be
employed. It is also essential to ascertain whether the condom was
used consistently and correctly, including occurrences of slippage or
breakage, during the entire period of exposure. Because direct
observation and objective measurement of condom use are not possible,
all studies must rely on self-reported use, a potential source of
error due to recall bias.3
The panel's review of the existing literature on condoms and STD
transmission revealed that the majority of the studies were not
optimally designed to answer the specific questions posed at this
workshop; as such, a number of common problems in study design were
noted including:
(1) In some STD studies, clinical manifestation of disease rather than
the more infection-specific diagnostic tests were used as the outcome
measures in evaluating condom effectiveness. Consequently, the study
designs were not optimal to ascertain all incident infections and,
therefore, to address the objectives of this conference.
(2) Many studies lacked sufficient numbers of subjects to have
adequate statistical power to evaluate condom effectiveness.
(3) Many studies were done in special populations, such as commercial
sex workers or STD clinic patients, who are at far higher risk for
infection than are other sexually active individuals. Therefore,
generalizability to other populations is somewhat limited.
(4) Gender differences with respect to infectivity and susceptibility
were not taken into account in many studies. For example women are
more susceptible than men to gonorrhea and chlamydia.
(5) Insensitive or non-specific methods were often used to detect
specific infections.
(6) Most studies did not use the optimal interview methods or
questionnaires to elicit complete and accurate information, especially
with regard to sexual histories and condom usage.
(7) Factors associated with the outcome disease that are also
associated with condom usage can confound and bias estimates of
effectiveness. Bias can either over-estimate or under-estimate
effectiveness.
3 New tests using biological markers assessing the presence or absence
of seminal fluids in the vagina after intercourse may offer the
possibility of better measurements of condom use and/or effectiveness.
The use of these biomarkers is promising but remains developmental.  

5July 20, 2001
(8) Many available studies had limited data regarding condom use in
relation to exposure to infectious agents. In many, quantitation of
condom use was imprecise and did not distinguish between correct and
incorrect use, e.g. timing of donning of the condom during sexual
activity and use of the condom during the entire sexual act. Slippage
and breakage events were also not quantified and some studies measured
only "ever" use and some failed to specify how condom use was
measured.
(9) For most studies the ability to document exposure to disease in
relationship to condom use was uncertain.  

4. Findings: The Device
The Latex Male Condom
Most male condoms are made from natural rubber latex. When used
consistently and correctly and without slippage or breakage, male
condoms cover the penis and will contain pre-ejaculate emissions as
well as semen following ejaculation, thus protecting the female
reproductive tract. Condoms also may prevent penile exposure to
cervicovaginal secretions and tissues under similar conditions and
use. Condom shape, thickness, and other specifications, including the
latex formulation itself, have been engineered to produce a product
that is placed easily (onto the penis), minimizes slippage and
breakage during vaginal intercourse, and contains the collected
fluids.
The FDA regulates manufacturers who sell condoms in the U.S.,
primarily through 510(k) premarket notification (premarket) and
compliance with the Quality System Regulation (postmarket). Through
premarket notification, FDA can ensure that condoms marketed in the
U.S. are designed properly with appropriate specifications. As a
postmarket regulatory control, the Quality System Regulation requires
manufacturers to:
(1) Employ quality assurance standards for new condom designs; (2)
Employ validated processes in condom manufacture; and (3) Apply strict
product release criteria to condoms.
As a quality assurance step, condom manufacturers sample each lot of
finished packaged condoms and visually examine them for holes using a
water leak test. FDA recognizes domestic and international standards
that specify that the rate of sampled condoms failing the water leak
test, for each manufacturing lot of condoms, be less than 1 in 400
(ASTM D3492 and ISO 4074) (http://www.fda.gov/cdrh/ode/oderp399.html).
Manufacturers also test lots for physical properties using the air
burst test and the tensile (strength) property test. These latter
tests provide a measure of consistent condom quality.
The FDA also requires manufacturers to determine condom stability over
time and to provide an expiration date of the condom for the labeling.
This is done  

6July 20, 2001
using accelerated stability tests of packaged condoms at elevated
temperatures. In addition, manufacturers must conduct real-time
studies to confirm the expiration date (21 CFR 801.435)
(http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi). Properly
packaged and properly stored, condoms maintain their physical
integrity over several years.
FDA researchers have also developed an assay for condom leakage using
high concentrations of a laboratory virus (78). The laboratory virus
penetration assay is not used routinely as a quality control test, but
its sensitivity and relevance are arguably greater than the
conventional water leakage test. Using this virus assay, FDA
scientists tested many different types of male condoms and showed that
condoms are highly effective barriers to virus passage with a very
small chance of leakage (76, 77). Intact condoms (i.e., pass the water
leak test) are essentially impermeable to particles the size of STD
pathogens (including the smallest sexually transmitted virus,
hepatitis B). Moreover, these studies show that fluid flow, not virus
size, is the most important determinant of viral passage through a
hole. Even holes many times larger than the virus impeded fluid flow
such that few of the test particles passed through (78).
Applying results from the laboratory tests (12, 76, 77, 78), the
hypothetical relative risk of exposure to semen, as a function of
semen volume attributable to various independent condom use events,
was presented and is shown in the table below. The purpose of this
relative risk assessment is to model the expected degree of protection
of exposure to semen afforded by condom use, condom non-use, and
condom use in the events of breakage or leakage.
Hypothetical Relative Risk Model of Condom Use  

7July 20, 2001
For example, if a condom breaks during intercourse, the associated
volume of fluid leaking out of the condom is estimated to be
approximately one-third of the total ejaculate, i.e., about 1 ml.
Therefore, assuming a 2% breakage or slippage rate during actual use,
the relative risk of semen exposure from the infrequent condom
breakage (compared to using no condom at all) would be .006 (1 ml ×
2/100 ÷ 3.3 ml).
Under this risk assessment, failure to use a condom would obviously
result in certain exposure (1.0 probability). Conversely, condom use
without breakage or slippage would reduce (if not eliminate) exposure
dramatically (0.0 probability). However, and perhaps just as
importantly, condom use - even in the event of breakage, leakage, or
slippage - would also result in greatly reduced exposures.
It should be noted that, for many STDs, risk of infection might not be
proportional to exposure to a volume of semen. Estimation of risk
requires further extrapolation because it depends on additional
variables, especially the infectious agent of interest. The
concentration, infectivity, and mode of transmission of the specific
STDs clearly need to be considered (12).
Conclusion
Natural rubber latex condoms for men are manufactured to conform to
limits specified within consensus standards, including water leakage.
Laboratory studies show that manufactured condoms meet these
specifications. Other studies, based on viral penetration assays, have
demonstrated that condoms provide a highly effective barrier to
transmission of particles of similar size to those of the smallest STD
viruses. These data also provide a strong probability of condom
effectiveness when used correctly, where the etiology of STD
transmission is linked to containment of pre-ejaculate and seminal
fluids or barrier coverage of lesions on the penis and there is no
slippage or breakage.
Condom Use Data
Condom use patterns
National surveys that monitor contraceptive behaviors among Americans
have documented increases in condom use throughout the 1980s and
1990s, coincident with increased awareness of AIDS and increased
prevention efforts. The largest increases in condom use have occurred
among adolescents and young adults, the age groups most at risk for
infection with HIV and other STDs. The National Survey of Family
Growth reported that condom use among American women 15-44 years of
age increased from 12% in 1982 to 15% in 1988, and to 20% in 1995
(98). Reported condom use in women is higher among those who are
unmarried and younger. The trends in National Survey of Family Growth
data are corroborated by data from national representative sample
surveys of youths. Two surveys of young men, completed in 1988 and
1995 document that in 1988, 33% of youth ages 15-19 report always
using a  

8July 20, 2001
condom when having sex, and in 1995 that proportion increased to 45%.
In 1988 the proportion of those who had sex and never used condoms was
18.4%, while in 1995, only 9.5% reported never using condoms (112).
The Youth Risk Behavior Survey (youth in grades 9-12) also documents
significant increases in reported condom use between 1991 and 1997,
from 55% to 62% for males and from 38% to 51% for females (180). That
study reports use at the last act of coitus, but does not address
correct or consistent use nor slippage and breakage. A 1990
re-interview of participants in the 1988 National Survey of Family
Growth assessed the reasons for condom usage in a representative
sample of 932 sexually experienced unmarried women (aged 17-44). In
this group 41% reported using condoms for protection, at least some of
the time, against STDs; 18.5% reported "every time" use (4).
Condom Slippage and Breakage during Use
For a condom to be fully effective, it must stay on the penis during
sexual intercourse, and it must not break. However, condoms sometimes
do slip or break during use. Many studies have looked at condom
slippage and breakage, but most were conducted ten or more years ago
and, therefore, do not represent higher quality condoms being
manufactured today. Moreover, most employed methodologies led to
questionable relevance or reliability of reported rates. Such
methodological drawbacks included inexact definition of terminology,
selection bias, study size (e.g., <100 couples; <1000 uses),
populations that are less generalizeable (e.g., commercial sex
workers, low STD risk, etc.), and reporting methods (e.g.,
retrospective surveys relying on memory of events six months earlier).
None of the studies considered by the panel evaluated condom slippage
and breakage rates in sexually active teenagers less than 18 years of
age. Only three published articles report results from recent
prospective sizeable trials of latex condoms in the U.S. and provide
reliable slippage and breakage rates (44, 45, 80). Estimates of condom
breakage from these studies range from 0.4-2.3%. Slippage rates from
these three studies ranged from 0.6% to 1.3%. Slippage rates include
both slippage during intercourse and slippage during withdrawal. The
combined method failure (slippage plus breakage) is estimated at 1.6%
- 3.6%.
These and other studies show that factors affecting slippage and
breakage are related to user familiarity and knowledge, including user
experience, selection of condom size (width), and proper use of
additional (exogenous) lubricant (2, 51, 81, 123). With increased
education and improved experience, one can expect condom slippage and
breakage rates to decrease.
One additional drawback of all these studies is reliance on
self-reports for tallying the events themselves, i.e., slippage,
breakage, and use. More recently, study methodologies have provided
for improved logs of coital activity to be used by study participants,
as well as careful study monitoring techniques to encourage their
consistent use. It is believed that this has added to the reliability
of slippage and breakage rates numbers. Still, these studies may
inherently be hindered by  

9July 20, 2001
relying on the self-assessment of study participants. Over the past
2-3 years, researchers have begun to use biological markers and
postcoital testing of the vaginal pool as a potentially more objective
measure of method failure. The eventual success of these efforts
remains to be seen (75, 79, 129).
Overall, results from clinical slippage and breakage studies, when
coupled with results from laboratory studies, suggest that condoms
provide a reliable barrier for the areas covered (the penis) and
touched (vaginal and cervical mucosa) and that the level of protection
is greatest when used correctly.
Lessons from Pregnancy Studies
Information on consistent and correct condom use for the prevention of
pregnancy has also provided valuable insights on the importance of
consistent use. Approximately 3% of couples who reported using condoms
consistently and correctly (considered "perfect use") are estimated to
experience an unintended pregnancy during the first year of use (123),
based on results of one rigorous controlled trial as well as modeling
based on rates of condom breakage and slippage. In a recent
well-controlled randomized clinical trial of monogamous couples using
latex male condoms for contraception over six months, the pregnancy
rate during "typical use" was reported at 6.3%, with a 1.1% pregnancy
rate during "consistent use" (45). Most of these couples had
experience using condoms. However, based on estimates from National
Surveys of Family Growth (123), 14% of couples are estimated to
experience an unintended pregnancy during the first year of "typical"
use, a failure rate that includes both inconsistent (non-use) and
incorrect use, as well as breakage and slippage. Failure rates in the
second year of typical use are about 50% lower (167).
Conclusions
Condom use in the U.S. has increased over the past 20 years. Recent
studies conducted in the U.S. show condom breakage rates during use to
be in the range of 0.4% to 2.3%, with comparable rates for slippage.
Use factors such as experience, condom size, and use of lubricant can
affect condom slippage and breakage.
Information on condom use for pregnancy prevention indicates that, at
least in the population described above, as condom experience and
facility in use of condoms increases in couples using condoms as their
primary method of birth control, unintended pregnancies decrease.  

10July 20, 2001
5. Findings: The Diseases
The eight STDs addressed in this report are HIV infection, gonorrhea,
chlamydial infection, (including PID caused by gonococcal and
chlamydial infections), syphilis, chancroid, trichomoniasis, genital
herpes caused by HSV 1 and 2, genital HPV infection and HPV diseases
including genital warts, cervical dysplasia and cervical cancer. These
infections span the spectrum of medical microbiology, including viral,
bacterial, and parasitic infections. Each of these infectious diseases
is unique; variation in transmissibility, duration of infectivity,
co-morbidity, and clinical manifestations are well described.
Variations in the modes of transmission and the transmissibility of
the different infections will affect the level of protection that
condoms can be expected to provide.
Seven of the eight STDs fall into two categories: discharge diseases
and ulcerative diseases. The discharge diseases include HIV infection,
gonorrhea, chlamydial infection and trichomoniasis. The infectious
agents of discharge diseases are present in genital secretions (i.e.,
semen and cervical-vaginal fluid). In genital ulcer diseases (genital
herpes, syphilis, and chancroid), the infectious agents are present in
sores or ulcers; however, the infectious agents may also be released
or "shed" into secretions. HPV infection cannot be classified in
either category; this virus is probably transmitted via contact with
infected cell surfaces in the presence or absence of fluid or tissue
exchange. Organism-related factors that influence transmission include
infectiousness of virus, bacterium or parasite, duration of
infectiousness, and variation in infectiousness based on stage of
disease.
In addition to causing symptomatic disease, most of these infections
cause diseases with no symptoms (asymptomatic) or with very mild
symptoms; these infections are called "silent." People who have silent
infections do not seek health care and consequently, most remain
undiagnosed and untreated. Not all STDs respond to treatment. The
curable diseases include four bacterial infections (gonorrhea,
chlamydial infection, syphilis, and chancroid) and the one parasitic
infection (trichomoniasis). Appropriate treatment eliminates these
infections. In contrast, the viral infections (HSV, HIV, and HPV)
either persist for life (HSV and HIV) or are cleared spontaneously
(approximately 90% of HPV infections). However, HSV and HIV infections
may be controlled or ameliorated with anti-viral therapies.
The likelihood of spreading these infections during sexual intercourse
varies. Multiple factors influence transmission, including
characteristics of the infectious organism and the site(s) of
infection, the health of the infected individual and the uninfected
partner, the couple's sexual behaviors, and the prevalence of STDs in
different populations will affect the likelihood of exposure to STDs.
A number of biologic factors, specific to the infected individual and
his or her partner influence transmission rates including age, sex,
and nutritional status.  

11July 20, 2001
Based on genetic make-up and history of previous infections,
individuals may vary in non-specific defenses and specific
(immune-mediated) defenses. These defenses will alter susceptibility
to infection if exposed. If the person is infected, host defenses may
alter that person's infectiousness by reducing the frequency of
shedding of the infectious agent, the concentration of the infectious
agent in secretions or lesions, and the duration of infection. Whether
or not a host becomes symptomatic during infection may influence
health care seeking behaviors that would also influence
infectiousness.
A couple's sexual behavior is important; specifically foreplay, the
types of sexual intercourse (e.g. anal and/or penile-vaginal),
abrasions, the number of acts of intercourse and intercourse during
menses may influence exposure and transmission rates. Importantly, the
duration and perceived seriousness of the relationship and the gender
roles and empowerment, will affect the use of condoms, choices of
contraceptive, and choices regarding sexual monogamy.
General population factors that influence transmission rates include
prevalence of infection and access to health care. The risk of
transmission of infection can vary widely in observed populations
because actual exposure depends upon the choice of individual sex
partner and that person's risk characteristics.
To complicate matters, a change in one factor may lead to other
changes that counter-act the anticipated change in risk of
transmission. For example, anti-herpes therapies (e.g., acyclovir)
reduce the amount of genital herpes virus that is shed in the genital
tract fluids. The expectation is that the person is less infectious
since these secretions may not contain much virus. However, if
infected individuals do not use condoms during intercourse because
they believe that they are not infectious, the rate of HSV
transmission may not be reduced. In aggregate, both biomedical and
behavioral factors determine whether or not infection is transmitted.
Measurement of condom effectiveness is affected by transmissibility;
the relative ease of transmission in part determines how "forgiving"
the method is if user- or device-failure occurs. If infection is
transmitted easily, for example gonorrhea, failure to use a condom or
incorrect use even one time may result in exposure and infection. In
contrast, if an infection is hard to transmit, for example HIV,
failure to use a condom or incorrect use may not result in infection
because the probability of transmission is lower per exposure.
Infections Transmitted by Genital Secretions
With penile-vaginal intercourse, HIV/AIDS, gonorrhea, chlamydia and
trichomoniasis are transmitted from infected males to uninfected
females via exposure of the cervix and vaginal epithelium to semen and
from infected females to uninfected males via exposure of the male
urethra to female genital secretions. The effectiveness of the latex
male condom in reducing the risk of infection is, in large part,
dependent upon preventing exposure to fluids that may  

12July 20, 2001
be infectious. If used correctly and without slippage or breakage, the
latex male condom contains the male pre-ejaculate and ejaculate and
thus reduces the risk that the female will be exposed to these
secretions. Likewise, if used correctly and without slippage or
breakage, the latex male condom should adequately cover the male
urethra and protect the penis from exposure to female genital
secretions.
HIV (Human Immunodeficiency Virus)/AIDS
Background
In 1999, an estimated 6 million adults and children around the world
were newly infected with HIV. Approximately 40,000 of these infections
occurred in the U.S; 70 percent of new infections were diagnosed among
men and 30 percent among women. Notably, more than 80 percent of all
adult HIV infections throughout the world have been transmitted during
heterosexual intercourse.
HIV is found in the blood and virtually all other body tissues and
fluids. Stage of disease as well as co-infection with other STDs can
increase HIV shedding in genital secretions and thereby increase risk
of transmission. HIV/AIDS can be sexually transmitted by anal,
penile-vaginal, and oral intercourse. The highest rate of transmission
is through anal exposure. In addition, secretions from ulcerative
lesions (associated with other STDs) on the penis may also be a source
of infected male-to-uninfected female transmission of HIV/AIDS, and
ulcerative lesions may be sites for uninfected male exposure to
HIV/AIDS from infectious female secretions.
Key Research Findings on Effectiveness
HIV infection is the only STD for which formal meta-analyses have been
published (28, 166). The most recent analysis by Davis and Weller (28)
was evaluated. This analysis, in which only longitudinal or cohort
studies were included, used the following criteria to select studies
related to condom use and HIV/AIDS prevention:
(1) Sample included serodiscordant, sexually active, heterosexual
couples; (2) HIV status was determined by serology (so that exposure
to HIV was
known); (3) Data collection included self report about condom use; and
(4) Study design afforded longitudinal follow-up of HIV uninfected
partner.
Studies with insufficient condom use information and/or duplicate or
interim reports on the same cohort were excluded.
Davis and Weller found twelve studies, which met these criteria (139,
29, 30, 150, 155, 158, 160, 161, 165, 108, 171, 173). The
meta-analysis noted the direction of transmission (male-to-female,
female-to-male, and unstated) and  


13July 20, 2001
date of study enrollment. Condom usage was classified into the
following three categories: always (100% use), sometimes, and never.
Among participants who reported always using condoms, the summary
estimate of HIV/AIDS incidence from the twelve studies was 0.9
seroconversion per 100 person years. Among those who reported never
using condoms, the summary estimate of HIV/AIDS incidence from the
seven studies was 6.7 seroconversions per 100 person years. Overall,
Davis and Weller estimated that condoms provided an 85% reduction in
HIV/AIDS transmission risk when infection rates were compared in
always versus never users.
Conclusions
The methodological strength of the studies on condoms to reduce the
risk of HIV/AIDS transmission far exceeds that for other STDs. There
is demonstrated exposure to HIV/AIDS through sexual intercourse with a
regular partner (with an absence of other HIV/AIDS risk factors).
Longitudinal studies of HIV- sexual partners of HIV+ infected cases
allow for the estimation of HIV/AIDS incidence among condom users and
condom non-users. From the two incidence estimates, consistent condom
use decreased the risk of HIV/AIDS transmission by approximately 85%.
These data provide strong evidence for the effectiveness of condoms
for reducing sexually transmitted HIV.  

Gonorrhea (Neisseria gonorrhoeae)
Background
Gonorrhea causes significant morbidity in the U.S. and around the
world. Every year an estimated 650,000 cases occur in the United
States and 62 million cases occur worldwide. Gonorrhea is one of two
major causes of pelvic inflammatory disease (PID); the other cause is
chlamydial infection. Although PID is often silent and therefore
difficult to diagnose, PID is a serious disease in the upper
reproductive tract of women. PID causes tubal scarring and can result
in ectopic or tubal pregnancy, tubal infertility, and chronic pelvic
pain. Like most other STDs, gonorrhea may cause adverse pregnancy
outcomes, such as neonatal ophthalmia, with loss of vision.
Infection results from exposure to Neisseria gonorrhoeae in infectious
cervical/vaginal secretions or ejaculate during oral, vaginal, or anal
intercourse. Although the infectious dose is unknown, one ejaculate
from an infected man contains approximately 6 million live bacteria
(157). Although limited, data suggest an average transmission of 1
infection for every two exposures. Transmission efficiency is gender
dependent. Females are at greater risk of acquisition, with 0.6 to 0.8
infections following a single exposure with an infected male. Males
are at less risk (0.2) from a single act of vaginal intercourse, with
cumulative risk increasing from 0.6 to 0.8 with four or more exposures
(61, 172).  


14July 20, 2001
Among men, symptoms typically appear within 2-5 days following
infection. Estimates from screening studies suggest that asymptomatic
disease occurs in approximately 10% of infected men. Among symptomatic
women, incubation periods vary. Asymptomatic disease occurs in 20 to
80 percent of infected women.
Three methods are generally used to diagnose gonorrhea - gram stain,
nucleic acid amplification tests, and culture. However, since gram
staining is not sensitive for detecting infections in women nucleic
acid amplification tests, or laboratory culture are usually used to
diagnose gonorrhea. The sensitivity and specificity of these two tests
are extremely high (approaching 98%) (147). Gonorrhea is curable with
single-dose therapy; currently cephalosporin or fluoroquinolone
antibiotics are used.
Key Research Findings on Effectiveness
Key Research Findings on Effectiveness
The panel reviewed thirteen studies on gonorrhea and condom
effectiveness. Four studies in men and two studies in women were
deemed acceptable for assessing gonorrhea transmission. The single
prospective study, among U.S. sailors having sex with commercial sex
workers, demonstrated that 0% (0/29) of men who sometimes or always
used condoms acquired gonorrhea compared to10.2% (51/498) of
non-users; however this difference was not statistically significant
(61). Two cross-sectional studies and one case-control study found
between a 49-75% reduction in risk of gonorrhea among men reporting
condom use compared to non-users (8, 96, 110). Only one of these
studies (8) reported measuring consistent and correct condom use. In
this study, a 71% reduction in relative risk for gonorrhea was
observed in men who reported correct condom use (4/106) compared to
men reporting incorrect use (20/153). One case-control study found no
significant risk reduction in gonorrhea cases when women who had ever
used condoms without other methods (98/706) were compared to women who
had never used condoms (126/889) during the previous three months (O.R
0.90) (6). Another cross-sectional study found a 39% relative risk
reduction in gonorrhea infection comparing women attending an STD
clinic who reported using condoms as a method of contraception
(93/984) to those who did not use condoms, sponges, or diaphragms as a
birth control method (521/4068) (105).
Two case control studies that used either pelvic inflammatory disease
(PID) or tubal infertility as outcome measures were also evaluated.
Although the PID study did not distinguish between PID due to
gonorrhea or chlamydia, a 55% relative reduction in the risk of PID
was observed among women who had ever used a condom in the previous
three months; 32/279 of women with PID reported condom use in the
previous 3 months compared to 213/959 who did not have
PID (absolute risk reduction 13.7%, relative risk reduction 55%) (69).
The
second study found a statistically insignificant effect on the risk of
tubal infertility  


15July 20, 2001
when at least three months of continuous condom use was compared to
non-use of condoms; 48/200 women with infertility reported three
months of continuous condom use compared to 679/2538 women without
infertility (absolute risk reduction 2.5%, relative risk reduction
30.5%) (25).
Conclusions
Several of the available studies on effectiveness demonstrated a
protective effect of condoms for men, although they were limited
either by retrospective design, inadequate measures of condom use, or
small sample sizes. The panel deemed, however, that the collective
strengths of these studies demonstrated that correct and consistent
condom use would reduce the risk of gonorrhea for men. The available
epidemiologic literature does not allow an accurate assessment of the
degree of protection against gonorrhea infection in women offered by
correct and consistent condom use.  

Chlamydial Infection (Chlamydia trachomatis)
Background
Chlamydial infection is the most common bacterial STD in the United
States, with an estimated three million new cases per year. Infections
caused by Chlamydia trachomatis are usually asymptomatic. This disease
is most common in sexually active adolescents and young adults.
Chlamydia is transmitted from infected male-to-uninfected female via
semen and from infected female-to-uninfected male via exposure of the
male urethra to infectious female genital secretions. Chlamydia is
transmitted more easily to women (179). Infected women may also
transmit chlamydia to their babies during birth resulting in neonatal
eye infection and/or pneumonia. Although curable with appropriate
antibiotic therapy, most chlamydial infections are asymptomatic and
thus go undiagnosed and untreated. Persistent infection often results
in PID; common sequelae include chronic pelvic pain, tubal pregnancy,
and infertility. Epididymitis in men is well documented, although
other chronic sequelae in men have not been thoroughly studied.
Key Research Findings
Review of the literature revealed twelve papers (10, 38, 42, 48, 63,
91, 101, 105, 107, 110, 137, 138) that, to some degree, addressed
condom effectiveness for prevention of chlamydial infection. However,
virtually all twelve studies were compromised by design weaknesses
(from the perspective of measuring condom effectiveness and
identifying exposure to infection).
Twelve studies, six were deemed sufficient for inclusion. Three
prevalence studies, two retrospective case-control analyses, and one
prospective study measured the relationship of self-reported condom
use and C. trachomatis infections. Of the three studies of infection
in women, two (63, 105) failed to  


16July 20, 2001
demonstrate a protective effect of condoms among high risk populations
including commercial sex workers in Indonesia who had ever used a
condom during the previous week (63) and women attending a STD clinic
in the U.S. who reported they were using condoms (105). Of the 1873
commercial sex workers, only 14% reported using condoms in the
previous week. In this study 10 % of 397 condom uses and 13% of 1005
non-users were diagnosed with chlamydia. In the cross-sectional study
of women attending a STD clinic, chlamydia infection was seen in 2/157
women who reported using condoms as a method of contraception and in
111/823 who did not use condoms, sponges or diaphragms as a birth
control method (105). The third study among 13,204 new female military
recruits found a statistically significant increase in chlamydial
infections associated with self-reports of no condom use or
inconsistent condom use (O.R. 1.4) (48).
Three studies, one prevalence (cross-sectional) study (137), one
case-control (110), and one prospective study (138) evaluated the
relationship between condom use and the risk of chlamydial infection
in men. The cross-sectional study found no evidence of reduction of
chlamydial infections associated with self-reported consistent condom
use among 356 heterosexual men attending a London hospital clinic
(137). For the subset that reported having "changed partners" in the 3
months prior to visiting the clinic, 11% of men (4/37) who reported
"always" using condoms and 12% of men (7/59) who reported "never"
using condoms were diagnosed with chlamydia infection. The
case-control study among 4,848 men attending a STD clinic in Seattle
found a 33% risk reduction among consistent condom users (which
represented approximately 12% of the clinic men) compared to any other
patterns of condom usage/non-usage, however this reduction was not
statistically significant (110). The third study, a prospective design
(138), found 0% (0/72) of men who reported always using a condom
developed chlamydial infections compared to 6.3% (16/251) of men who
reported sometimes or never using condoms, a statistically significant
effect.
Conclusion
The one study employing a prospective design found a protective effect
of condoms against female-to-male transmission of chlamydia. Other
studies in men and women demonstrated either no or some protection and
are inconclusive. Taken together, the available epidemiologic
literature does not allow an accurate assessment of the degree of
potential protection against chlamydia offered by correct and
consistent condom usage.  

Trichomoniasis (Trichomonas vaginalis)
Background
Trichomoniasis is caused by Trichomonas vaginalis, a protozoan
parasite. It is responsible for an estimated 5 million symptomatic
cases of vaginitis per year in  


17July 20, 2001
the United States and 160 million cases worldwide. In men, infection
is associated with urethritis, prostatitis, and other syndromes.
Trichomonas vaginalis is transmitted from infected males to uninfected
females and from infected females to uninfected males via exposure of
mucosal surfaces to genital secretions. Asymptomatic infection occurs
in both men and women. Diagnosis is commonly made by direct
microscopic examination of genital specimens, but this method has low
sensitivity when compared with culture. As with other STDs,
trichomoniasis has been associated with increased transmission of
HIV/AIDS. Transmission rates for T. vaginalis have not been measured
but are estimated to be high. The infectious dose is also unknown.
Treatment with single-dose, inexpensive, oral therapy (metronidazole)
results in high cure-rates.
Key Research Findings
A statistically significant reduction in trichomonas infection (30%)
was reported in women attending a STD clinic who reported using
condoms as a method of contraception (106/1021) compared with those
who did not use condoms, sponges or diaphragms as a birth control
method (525/4660) (105). Other published data employed designs that
rendered them inadequate to allow evaluation of the effectiveness of
condoms in preventing transmission of trichomoniasis.
Conclusions
One limited study demonstrated a 30% protective effect for women. The
paucity of epidemiologic studies on condom effectiveness for
trichomoniasis does not allow an accurate assessment of the reduction
in risk of trichomoniasis offered by condom usage.  

Genital Ulcer Diseases
In genital ulcer diseases (genital herpes, syphilis, and chancroid),
the infectious agents are present in sores or ulcers. However, these
infectious agents may also be released or "shed" into secretions. The
potential of the latex male condom to reduce the risk of transmission,
even when used correctly and without slippage or breakage, would be
expected to depend on the site of the sore/ulcer or infection and the
ability of the condom to fully cover the lesion.  

Genital Herpes (Herpes Simplex Virus Types 1 and 2)
Background
HSV 1 and HSV 2 cause oral and genital herpes. Using HSV-2 serology as
a surrogate marker, at least 45 million Americans are infected with
genital herpes, with 500,000 new infections and 10 million recurrences
occurring every year. Genital herpes can also increase the risk of
HIV/AIDS transmission and acquisition.  


18July 20, 2001
Lesions on anogenital sites and surrounding areas (buttocks and
thighs) are common in symptomatic infections. However, it is estimated
that more than 80 percent of primary and recurrent genital infections
are undiagnosed because the infections are usually asymptomatic or
unrecognized. Genital herpes is transmitted from males to females by
contact with infected genital skin or mucosal surfaces, including
either apparent lesions or areas with inapparent infection. For the
male, the penis (skin and urethra) is the genital area most often
affected, but other genital areas may also be affected (145). Herpes
is transmitted from females to males by contact with infectious
secretions or infected genital-area lesions, which are usually vulvar,
vaginal, or cervical and which may be apparent or inapparent. Viral
shedding occurs in the presence or absence of symptoms. Recent studies
have suggested that viral shedding can occur, on the average, 28% of
days that subjects are followed; asymptomatic shedding can result in
transmission (175). Furthermore, genital herpes can result in
maternal-to-infant transmission of infection at delivery, which can be
fatal (142).
Because other infections cause genital ulcers, the gold standard for
diagnosing genital herpes is by culturing the virus from ulcers. Other
diagnostic procedures that utilize samples from lesions are polymerase
chain reaction and antigen detection tests. Given a history of genital
lesions, if a patient is examined after lesions have healed,
serological testing may help to diagnose genital herpes and to
differentiate between primary or recurrent infection. Based on viral
culture and/or nucleic acid detection, HSV-1 infection causes
one-third of genital herpes infections, and HSV-2 infection causes
two-thirds of genital infections (145).
An adequate study design to assess the effectiveness of condom use in
reducing the risk of genital herpes must take into account the natural
history of HSV infection, as follows:
(1) Most people with genital HSV infection do not know they have
genital herpes. (2) HSV causes a latent, persistent infection that
reactivates and can cause
recurrent disease (both clinical and subclinical). (3) People with
genital herpes cannot always tell when the virus reactivates. (4) New
infections can only be measured by evidence of seroconversion
using accurate tests.
Key Research Findings on Effectiveness
A search of the literature revealed five prevalence (cross-sectional)
studies that allowed for assessment of condom effectiveness for
preventing HSV transmission. None of the studies reviewed was designed
specifically to measure condom effectiveness for preventing HSV, but
all did include some measure of condom use. A cross-sectional survey
of 766 women in Costa Rica showed a partial protective effect
(approximately a 30% reduction in herpes  


19July 20, 2001
seroprevalence) among women who reported their male partners ever
using condoms (28.9%) compared to those reporting never using condoms
(44.3%) (90). Another population-based study of 1600 randomly selected
women done in Greenland and Denmark showed a non-significant
relationship between HSV-2 infection among women who reported ever
using barrier contraceptive methods, either condoms or diaphragms, and
those that did not use barrier methods (O.R .85) (72). Two serological
studies, one in 1,115 young Thai army conscripts (149) and the other a
random sample of 259 women and 231 men in rural Tanzania (162)
evaluated the history of condom use and its association with HSV
seroprevalence. In the Thai army study, although the consistent use of
condoms in the previous 3 years during sex with commercial sex workers
was associated with significantly increased seroprevalence for either
HSV-1 or HSV-2, (O.R.1.8), seroprevalence decreased consistently with
increasing regularity of condom use (O.R. .79). In the Tanzania study,
reported rates of condom use were too low in women to examine their
association with HSV-2 infection. Among Tanzanian males, the
prevalence of HSV-2 was higher in men who used condoms (O.R. 2.99) but
condom use among males was reported to be a marker for high-risk
relationships, e.g. intercourse with sex workers. Because the study
did not report data on high-risk relationships, no meaningful
conclusions were drawn regarding condom effectiveness (162). A study
of 135 adolescents in juvenile detention facilities showed no
relationship between regular condom use (defined as used in >50% of
sexual contacts) and current HSV-2 status (156). Measurement of condom
use varied widely across these studies. None of the studies assessed
consistency of condom use over the entire period during which exposure
to HSV could have occurred.
Conclusions
The limitations in epidemiologic study designs and the lack of primary
outcome measurements found in the above studies prevented the Panel
from forming any conclusions about the effectiveness/ineffectiveness
of correct and consistent condom usage in reducing the risk of genital
herpes infection.  

Chancroid (Haemophilus ducreyi)
Background
Chancroid is a bacterial infection caused by Haemophilus ducreyi. It
is a major cause of genital ulcer disease in many areas of the world,
especially Asia and Africa. Chancroid is transmitted from infected
male to uninfected female via genital-area lesions that are usually,
but not always, on the penis, and from infected female to uninfected
male via exposure of the penis to genital area lesions that are
usually, but not always, in the vagina. Approximately 1,000 cases of
chancroid are reported in the United States per year. However, because
the organism is difficult to culture, it is likely that some cases are
not diagnosed. In the Southeastern region of the United States,
periodic outbreaks of chancroid have occurred.  


20July 20, 2001
In experimental models, the infectious dose is only a few H. ducreyi
organisms, if applied to abraded skin (176). Predictably, transmission
efficiency is high during sexual contact; transmission occurs in
approximately 70 percent of sexual exposures (177).
If untreated, lesions may persist for up to 3 months. In patients who
do not have syphilis, chancroid is often presumed to be the cause of
genital ulcer disease. Since culturing this organism is very
difficult, diagnosis by culture is not generally available. As a
consequence, a broad-spectrum antibiotic is used to treat these
patients. Like other genital ulcer diseases, chancroid facilitates HIV
transmission and acquisition.
Key Research Findings on Effectiveness
A limited number of studies are available due, in part, to the low
incidence of disease in the U.S. and in part to diagnostic
difficulties. Only two studies are relevant to this review. In
Thailand, an HIV/AIDS control program that consisted of multiple
interventions including sanctions against sex workers if they did not
use condoms, mass distribution of condoms, mass media campaigns and
establishment of 140 new STD clinics, resulted in increased condom use
among sex workers and was associated with a 23%/year decrease in
chancroid cases over 4 years (53). From 1989 to 1993, there was a
reduction in reported chancroid cases from 29,675 to 1,990. However,
in this study the direct effect of condom use in the over-all
reduction in chancroid infection was not evaluated (53). In a point
prevalence study of sex workers in a chancroid endemic area of Kenya,
there were less GUD cases for those who always used condoms (18%,
N=28) compared to those who never used condoms (47%, N=17) (11). Since
neither study included microbiological confirmation of the disease,
attributing the effect of condom use to reduced risk of chancroid is
not possible.
Conclusions
Although both reviewed epidemiologic studies suggest an association
between condom use and the reduction in risk of chancroid infection,
the lack of microbiological confirmation prevented the panel from
drawing conclusions with respect to correct and consistent condom use
and the acquisition of chancroid.  

Syphilis (Treponema pallidum)
Background
Syphilis is a major cause of genital ulcer disease. In 1995, an
estimated 12 million new cases of sexually acquired syphilis occurred
globally. Following the epidemic of the 1990s, the rates of syphilis
in the United States have declined steadily. Currently, the United
States is experiencing its lowest rates of syphilis (2.2/100,000)
since the advent of effective antibiotic therapy. However, since  


21July 20, 2001
1997 increases in the incidence rates have been observed in cities
among men who have sex with men (e.g., Seattle, San Francisco, New
York). Furthermore, the reported rate of primary and secondary
syphilis among African Americans remains approximately 30 times higher
that the rate among whites (148).
The infectious bacterium, Treponema pallidum, is transmitted easily
through contact with moist, infectious lesions. The spirochete does
not invade intact skin and particles of the same diameter do not pass
through intact condoms. However, only a few organisms in contact with
skin abrasions are required to transmit infection. Acute disease,
which is communicable, includes the primary stage (ulcers) and
secondary stage (various lesions that may involve skin, mucous
membranes, or other tissues). The primary ulcers are often painless
and can be located on/around the genitals, mouth or, perianal area.
Women may have subclinical cervical/vaginal lesions. Chronic disease
(after the secondary stage) can be latent or develop into a systemic
illness affecting many organs. Infection during pregnancy can cause
fetal death or congenital syphilis. The diagnosis of primary syphilis
can be made by microscopic examination of material scraped from the
ulcers or by detecting antibodies in blood. Early stages of syphilis
are curable with single or multiple antibiotic injections. Secondary,
latent, and tertiary syphilis are diagnosed with blood tests. The
ulcers of early syphilis increase the risk of HIV acquisition and
transmission.
Non-sexual transmission may occur through body fluids such as blood,
lesion exudates, and breast milk. Transmission risk is greatest in the
first few months of infection, but may theoretically extend up to 2 to
5 years of latency, albeit at reduced and intermittent infectiousness.
Key Research Findings on Effectiveness
There were eight reports available for the purposes of this review.
These studies included case-control, cross-sectional, and ecologic
designs. All of these studies were limited by inadequacy of the data
on condom use, presumed limited exposure (because of low prevalence of
infection), and in several, small sample sizes reduced statistical
power. Two cross-sectional studies (8, 96) showed a 60-70% reduction
in the prevalence of syphilis infection among condom users compared to
others, although the results were not statistically significant. Both
studies assessed condom use in STD clinic patients, although one study
(8) compared correct and consistent use to incorrect use or no use. In
this study, 1.02% of all clinic patients (36/3543) had a syphilis
diagnosis compared to 0.39% (1/259) of patients who reported correct
and consistent use of condoms. Pemberton (96) evaluated the
distribution of STDs in males as they related to condom use. Of the
1,173 diagnoses, 51 cases of syphilis were identified. When cases were
evaluated based on condom use, 0.9% (1/112) of patients who reported
using a condom had syphilis compared to 2.7% (23/855) of non-condom
users. A third cross-sectional study (47), showed no significant
association between consistent condom use in the past year and a
positive syphilis serology among transvestite prostitutes. Among those
reported "always" use of condoms  


22July 20, 2001
there was a 72.2% (13/18) sero-positivity compared with 81.6% (40/49)
of those reported "inconsistent or never" use of condoms. A fourth
cross-sectional study (125) reported no association between condom
users (not further specified) and syphilis serology in female
commercial sex workers in Mexico City. A fifth cross-sectional study
among female commercial sex workers in Indonesia found that women
reporting "any condom use in the past week" had a statistically
significant lower prevalence of syphilis than those reporting no
condom use (8% {30/380} versus 14% {141/1006}) (63). A cross-sectional
study of 693 men and women attending municipal health centers in Peru
found no significant association between a history of ever-using
condoms (58%) and infection with STDs (syphilis, chlamydia, or HSV-2);
however, this study did not separately examine the relationship
between syphilis and condom use (107). A case-control study among 144
STD clinic attendees found a statistically significant reduction (59%)
in syphilis infection for persons reporting "any" versus "no" condom
use in the past 3 months (39). Lastly, in an ecologic analysis of
trends in syphilis and condom use among 824 commercial sex workers in
Japan, a decline in syphilis infection (from 7.5% to 0.5% between
1990-1993) occurred while condom use increased (6.3% to 25.3% during
the same period); however, this study did not directly assess the
relationship between condom use and syphilis infection among
individual women (117).
Conclusions
While most of the studies suggest a protective effect, all are
hampered by design limitations. Due to these limitations, the panel
found that no rigorous assessment of the degree of reduction in the
risk of syphilis transmission offered by correct and consistent condom
use could be made.
Non-classified modes of Transmission:  

Human Papillomavirus (HPV)
Genital HPV infection cannot be classified exclusively as either an
STD which is transmitted by genital secretions or which is transmitted
through contact with open sores. HPV is probably transmitted through
contact with infected epithelial surfaces and/or genital fluids
containing infective viruses.
Background
An estimated 20 million Americans are currently infected with genital
HPV (170). More than 50% of sexually active adults are estimated to
have once been infected with one or more genital HPV types,
significant majorities of which are subclinical, unrecognized and
benign (146).
There are more than 100 different types of HPV (174), differentiated
by their DNA and identified by number (e.g. HPV type 6, 11,16). A
subset of specific HPV types commonly infects the mucosal epithelium
of the genital tract and is sexually  


23July 20, 2001
transmitted. Genital HPV types can be further separated into high-risk
and low-risk HPV types. High-risk types are defined as causally
associated with cervical cancer (141), as well as forms of
anal/genital cancer and pre-cancerous tissue changes of the cervix
(cervical intraepithelial neoplasia or CIN) (143, 146). The low- risk
types cause genital warts and flat wart-like lesions of the cervix
called condylomata and/or low-grade Pap smear abnormalities
(dysplasia) (146). Low-risk types are rarely, if ever, associated with
cancer in immune-competent individuals, although multiple types of HPV
can often occur together.
The current definitive method of detecting HPV infection is laboratory
diagnosis by nucleic acid detection using tests such as DNA polymerase
chain reaction (PCR) or Hybrid Capture II (Digene Corp., Gaithersburg,
MD). Nucleic acid (DNA) testing for HPV is far more sensitive than
presumptive diagnosis of HPV infection through cytology (Pap smears)
or through clinical examination (observation of genital warts,
cervical condylomata, and/or cervical pathology determined through
colposcopy and biopsy). Older research literature on HPV and condoms
involves incomplete case ascertainment, as it relied only on cytology
or clinical examination prior to availability of HPV-DNA technology.
The natural history of HPV infection in men is poorly understood
(146). In women, genital HPV infections are common, but the vast
majorities are self-limiting (154, 60, 146, 168). Cross-sectional
studies have demonstrated that prevalent HPV infection of the genital
tract can be detected in approximately 30% of sexually active
adolescent girls and young women (140, 143, 151, 169). Studies on the
natural history of HPV in women of this age group indicate that the
majority of HPV infections (both high risk and low risk) result in
transient cervical tissue changes that are spontaneously cleared.
Persistent HPV infection may reflect an inability of the immune system
to clear the infection; persistent HPV infection is a prerequisite to
cervical disease progression (143). Studies have also consistently
supported a long duration of HPV infection prior to development of
cervical cancer (120, 146).
Unlike other STDs, HPV infection has not been associated with an
increased risk of HIV/AIDS acquisition. However, persons already
infected with HIV/AIDS appear to be at greater risk of acquiring or
reactivating HPV infection (146). Further, it is reasonable to assume
that the normal duration and natural history of concurrent HPV
infection may be altered as HIV infection damages the immune system,
leading to an increased incidence of cervical neoplasia in women (146)
and anal cancers in HIV-positive individuals (164).
Genital HPV infection is transmitted primarily by sexual contact.
Transmission occurs through contact with infected genital area skin or
mucosal surfaces/fluids, from either apparent or subclinical lesions.
HPV infection in women can occur on the cervix, vagina, vulva, inner
thighs, and perianal area (146). For the male, infections can occur on
the penis, urethra, scrotum, inner thighs and perianal area. Finally,
genital HPV types have also been isolated from skin and nail samples
of the hand in persons with genital warts (113); thus, digital
transmission  


24July 20, 2001
of HPV may be possible. Given that HPV infections can occur in and be
transmitted by areas not covered or protected by the condom, correct
use without breakage or slippage of the male latex condom could at
most be expected to partially reduce the risk of HPV transmission.
Key Research Findings on Effectiveness
Twenty-four papers were provided for consideration; 16 were found
adequate and are discussed in this review. These include 11
case-control studies (9, 31, 56, 59, 68, 70, 85, 111, 120, 131, 134),
four cross-sectional studies (1, 58, 62, 135), and one cohort study
(60).
The primary outcomes that were measured in these studies differed as
noted below, but include HPV infection, genital warts, low- and
high-grade cervical intraepithelial neoplasia (CIN), and invasive
cervical cancer. The 16 studies listed above investigated HPV
infection and/or HPV-associated disease outcomes only in women, with
the exception of one study that investigated HPV prevalence and risk
factors in only men (58), and one that measured genital warts in both
men and women (134).
Four of these studies looked at condoms as a factor in the risk of
acquiring HPV infection (60, 62, 68, 135). None of these four studies
reported a risk reduction for HPV infection associated with condom
use, including the one cohort study (60). Genital warts were
investigated in two retrospective studies (58, 134). In both studies,
investigators found that condom use provided some risk reduction from
warts among men (risk reduction of 30% and 52%). The one study (134)
that examined the effect of condom use on genital warts among women
found no statistically significant evidence for risk reduction (risk
reduction of 30%). Cervical dysplasia, carcinoma in situ, or invasive
cancers were examined in relation to condom use in 10 case-control or
cross-sectional studies (1, 9, 31, 56, 59, 70, 85, 111, 120, 131). Of
these 10, six studies reported that condom users had statistically
significant reductions in risk, ranging from 39% to 80% (1, 59, 70,
111, 120, 131). Among the remaining four studies, two noted risk
reductions that were not statistically significant (9, 31), and two
found no evidence of partial protection (56, 85).
Conclusion
The Panel found interpretation of the studies on condom use and HPV
infection/disease to be more difficult than for the other STDs. This
is due, in part, to the conflicting evidence reported by different
studies and the various different outcomes requiring evaluation.
Furthermore, most of the reviewed studies did not obtain sufficient
information on condom use to allow careful evaluation of the
association between correct condom use without breakage and HPV
infection or disease. For retrospective studies that focused on the
long-term disease outcomes, this was also complicated by the
difficulty in ascertaining condom use at relevant time points (i.e.,
years preceding the diagnosis of disease).  


25July 20, 2001
The HPV data were evaluated separately for the various outcomes of
interest (HPV infection, genital warts, and cervical neoplasia). There
was no evidence that condom use reduced the risk of HPV infection, but
study results did suggest that condom use might afford some reduction
in risk of HPV-associated diseases, including genital warts in men and
cervical neoplasia in women.  


6. Research Needs and Challenges
The foregoing review underscores the need to conduct better-designed
studies to assess condom effectiveness for STD prevention. Such
studies will continue to face complex design and ethical challenges.
Critical design elements include the following:
(1) A description of the type of condom used during each sex act.
Ideally, this
would include the brand, type and physical properties of condom as
well
as information on lubricant usage. (2) Frequency and specificity of
specific sexual acts. (3) Frequency and specificity of condom use,
including correctness of use, timing of donning and removal and any
slippage and breakage. (4) Validated and sensitive measurements (e.g.
biomarkers) of exposure,
infection and/or disease outcome. (5) Prevalence of infection in the
population. (6) Selection of study population and the generalizability
of this population's
results to other relevant populations.
In addition, there are important, potentially confounding variables
that need to be considered, such as concurrent contraceptive use,
other sexual acts (besides penile-vaginal intercourse) hat may result
in infection transmission, relationship characteristics (e.g., long-
or short-term; single partner or not) and partner characteristics
(history of STDs, injection drug use or other possible source of
infection).
The choice of study design will influence the inferences that can be
made from the data collected. As previously discussed, a prospective
randomized design provides the strongest clinical evidence for
effectiveness. However, because randomly assigning participants to a
condom non-use control condition is not ethical, observational study
designs must be used to assess the effectiveness of condom use to
prevent STDs.
Study design issues, already complicated by the limitations imposed by
an observational design, are made even more complex by the need to
address fundamental ethical principles, including the following:  

26July 20, 2001
(1) Research participants with curable STDs must receive timely
treatment. Studies of couples in which only one partner is infected
with an incurable STD (e.g., HIV/AIDS or HSV) must include the best
available preventive services, including provision of condoms and
condom counseling to the couples.
(2) All study participants must be informed of and have access to the
best available preventive measures.
(3) Because consistent condom use has been shown to reduce the risk of
some STDs, research participants cannot be ethically randomized to use
and non-use groups to assess the effectiveness of condoms. Withholding
condoms would be similar to withholding available treatment.
There are multiple distinct challenges to designing future studies
that could draw clear conclusions about effectiveness of condom use in
preventing STDs. STD treatment can reduce infectiousness, making
conclusions about condom effectiveness less certain and increasing the
necessary sample size. Effective prevention services, including
counseling and education, might increase participants' ability and
intention to use condoms, perhaps moving some participants from the
inconsistent-user category to the consistent-user category during the
course of the study.
Conclusions
The ability to definitively demonstrate the presence or absence of a
relationship between consistent and correct condom usage and the
reduction in risk of STDs was significantly hampered by the lack of
adequate study design in most, but not all studies under review.
Exceptions to this generalization are the studies that demonstrated
that the consistent use of male condoms protects against HIV/AIDS
transmission between women and men. Gonorrhea transmission to men was
also found to be reduced with consistent and correct condom use.
Better research is necessary to adequately answer the question about
condom effectiveness in reducing the risk of acquiring other STDs.
Notwithstanding numerous design and ethical challenges, it is
important that robust research be pursued to ascertain the true
benefits and limitations of an available risk reduction
technology-latex male condoms--for preventing the transmission of
STDs. At the same time, research on additional prevention technologies
and behavioral interventions must also be pursued in order to advance
the health of the public in the U.S. and abroad.  

27





July 20, 2001
Appendix B
Scientific Evidence on Condom Effectiveness for STD Prevention
June 12-14, 2000
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