Scientists: Smallpox vaccine slowed spread of HIV

George Mason University researchers say in a new study that the eradication of smallpox might have inadvertently aided the spread of HIV. In fact, the vaccine used to wipe out smallpox offered some protection against the AIDS virus and, now that it is no longer used, HIV has flourished.

Smallpox immunization was gradually withdrawn from the 1950s to the 1970s, following the worldwide eradication of the disease, and HIV has been spreading exponentially ever since. Currently, only scientists and medical professionals working with the disease are vaccinated.

To test their hypothesis, researchers looked at the white blood cells taken from people recently immunized against smallpox and tested how they responded to HIV. They found significantly lower replication rates of HIV in blood cells from vaccinated individuals, compared with those from unvaccinated controls, according to the BBC.

"There have been several proposed explanations for the rapid spread of HIV in Africa, including wars, the reuse of unsterilised needles and the contamination of early batches of polio vaccine," lead researcher Raymond Weinstein tells the BBC. "However, all of these have been either disproved or do not sufficiently explain the behavior of the HIV pandemic," Weinstein adds.

But they say in the journal BMC Immunology it is too early to recommend smallpox vaccine for fighting HIV.

- check out the study in BMC Immunology
- read the CBS News report
- see the BBC's coverage