From the website of the Food and Drug Administration
of the United States:

http://www.fda.gov/Cber/vaccine/thimerosal.htm

"The United States Code of Federal Regulations (the CFR) requires, in
general, the addition of a preservative to multi-dose vials of
vaccines; indeed, worldwide, preservatives are routinely added to
multi-dose vials of vaccine. Tragic consequences have followed the use
of multi-dose vials that did not contain a preservative and have
served as the impetus for this requirement. One particularly telling
incident from Australia is described by Sir Graham S. Wilson in his
classic book, The Hazards of Immunization

   In January 1928, in the early stages of an immunization campaign
against diphtheria, Dr. Ewing George Thomson, Medical Officer of
Health of Bundaberg, began the injection of children with toxin-
antitoxin mixture. The material was taken from an India-rubber-capped
bottle containing 10 mL of TAM. On the 17th, 20th, 21, and 24th
January, Dr. Thomson injected subcutaneously a total of 21 children
without ill effect. On the 27th a further 21 children were injected.Of
these children .eleven died on the 28th and one on the 29th. (Wilson
1967)

This disaster was investigated by a Royal Commission and the final
sentence in the summary of their findings reads as follows:

   The consideration of all possible evidence concerning the deaths
at Bundeberg points to the injection of living staphylococci as the
cause of the fatalities.

From this experience, the Royal Commission recommended that biological
products in which the growth of a pathogenic organism is possible
should not be issued in containers for repeated use unless there is a
sufficient concentration of antiseptic (preservative) to inhibit
bacterial growth."

Citizen Jimserac