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Medical Forum / General / General / October 2005H5N1 vaccine
I'm not a medical expert, but I read a lot. What guarantee do we have that we can really produce an effective vaccine against this thing? Dr. Gupta pointed out that the only way to be sure would be to knowingly expose healthy people to a virus with a 50% plus mortality rate and see if it works, something we are not likely to do. In addition, the yet to occur mutation of the virus that makes it easily transmissible might render any existing vaccine useless. If a mutated version of H5N1 spread quickly, would there be time to develop an effective vaccine? Influenza was the agent used in the Stephen King's 'The Stand', a biological weapon that decimates humanity. The rabies-like virus in Michael Boyle's 'Full Circle' is a natural event, and it also wipes out most of humanity. Tom Clancy used Ebola in two of his novels, and the fact is we can't treat any of the hemorrhagic fevers. I know these are all works of fiction, but The Black Death, The Plague of Justinian, and the Spanish Flu were not. I wonder if maybe we are too trusting and complacent about the possibility of a great pandemic. Of course, I also wonder if that might be a good thing. Worrying about something beyond our control can be unhealthy too, I guess. Oops, time for me to shut up now. Per Ddawg: >I'm not a medical expert, but I read a lot. What guarantee do we have that >we can really produce an effective vaccine against this thing? I'd put myself in the same boat with you: read a lot, don't claim any expertise. Having said that, I'd guess the whatever assurance we get will be from experiments on laboratory animals. One piece of advice I got from somebody who probably *does* know is to not be among the first getting vaccinated with any new vaccine - especially one that was rushed into production. I translate this to the old "Avoid buying release 1.0 of anything - wait for at least the bug fix release." He cited the 1967 vaccine's adverse effects on some people as an example. >In addition, the yet to occur >mutation of the virus that makes it easily transmissible might render any >existing vaccine useless. If a mutated version of H5N1 spread quickly, would >there be time to develop an effective vaccine? From what I've read so far, not only are there problems with producing H5N1 vaccines (the stuff kills the chicken embryos used in production too quickly) but there is also a very long lead time needed (like almost a year) and, finally, there is a lack of surge production capacity. i.e. there will be no time.  SignaturePeteCresswell > Per Ddawg: > >I'm not a medical expert, but I read a lot. What guarantee do we have that [quoted text clipped - 23 lines] > -- > PeteCresswell >From a public health blog: http://effectmeasure.blogspot.com/ H5N1 "An article in press at the journal Virology by Gambaryan and her Russian and CDC colleagues has interesting, and somewhat disquieting data on the evolution of H5N1. As noted in somewhat more detail on our Primer II piece at the Flu Wiki, influenza viruses adapted to birds have a slightly different predilection for binding to cells than those adapted to humans. To infect a cell the virus looks for a "receptor" on the cell's surface, essentially the door it uses to enter. The receptor for influenza viruses is a combination of a fat, sugar and protein tipped by sialic acid. How the sialic acid is connected (what kind of linkage) seems to be one determinant for a preference for bird cells or human cells. Bird viruses prefer the a 2-3 sialic acid linkage while human viruses prefer a 2-6 linkages. The a 2-3 links are characteristic of the intestinal tract of birds, while the a 2-6 linkages are the predominant receptors in the human respiratory tract. However it was recently reported that humans also have a significant number of a 2-3 receptors (on ciliated cells) in the respiratory tract and it is likely through these cells that the H5N1 virus transmitted from chickens grabs on and replicates. We don't know why it doesn't happen more often, however. The human virus seems to prefer to start off in the a 2 -6 linked cells. This is apparently not a problem in the intestinal tract of birds." http://effectmeasure.blogspot.com/
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