Contaminating viruses and the poliovaccines: cancer and AIDS

Contamination of cultures or cells used for research, therapy or vaccines is always possible. Poliovaccines were contaminated with a simian virus which had the potential to produce cancers, and several people have suggested that contaminated polioviruses were responsible for the AIDS epidemic, If such episodes and theories are to be discussed by students, discussion should be based on all the evidence available, not just on newspaper or popular articles. The contamination of poliovaccines is also discussed. When such contamination is Found, what con or should be done to discover if vaccines will suffer harm is a difficult question. Theories of the origin of AIDS are not scientific as they cannot be disproved. Nevertheless, it is important that students examine ail the evidence to see if the theories are likely or far-fetched. If the public desperately wants a vaccine, could scientists or governments withhold it on the basis of possible unknown and unknowable risks?