VALHALLA, N.Y., June 18, 2004 — A New York Medical College microbiologist warns that live virus vaccines to prevent infectious diseases like West Nile virus and yellow fever could have dire consequences. Should one of the vaccine flaviviruses recombine with a wild-type virus, a new microbe with potentially undesirable properties could result, according to Stephen J. Seligman, M.D., research professor of microbiology and immunology.
Flaviviruses, which can recombine within species and may recombine between species, also include dengue, Japanese encephalitis and tick-borne encephalitis. They cause substantial sickness and death each year. Although live-virus vaccines offer great promise in terms of cost and efficacy, their use should be approved by an international authority due to safety concerns, the authors write.
The article lists five main lessons learned from other live virus vaccines:
* reversion of vaccine strains to increased virulence;
* development of disease in individuals with compromised immune systems;
* birth defects, particularly if the vaccine is given in the first trimester;
* spread of vaccine strains to unvaccinated persons and;
* the discovery of new, previously undetermined complications.
Source: New York Medical College. June 2004.