Did end of smallpox vaccinations hike HIV?

FAIRFAX, Va., May 20 (UPI) -- U.S. scientists suggest the end of widespread small pox vaccinations toward the end of the 20th century might have resulted in the rapid spread of HIV.

Dr. Raymond Weinstein of George Mason University and a team of researchers from UCLA and George Washington University said the vaccine given to prevent the spread of smallpox produces a five-fold reduction in HIV replication in the laboratory. That, they said, suggests ending smallpox vaccinations might have caused a loss of protection against the human immunodeficiency virus.

The researchers said they looked at the ability of white blood cells taken from people recently immunized against smallpox to support HIV replication compared to unvaccinated controls. They found significantly lower viral replication in blood cells from vaccinated individuals.

"There have been several proposed explanations for the rapid spread of HIV in Africa, including wars, the reuse of unsterilized needles and the contamination of early batches of polio vaccine. However, all of these have been either disproved or do not sufficiently explain the behavior of the HIV pandemic," Weinstein said. "Our finding that prior (smallpox) immunization … may provide an individual with some degree of protection to subsequent HIV infection suggests the (widespread) withdrawal of such vaccination may be a partial explanation."

The study is reported in the journal BMC Immunology.