A cold germ is seemingly to blame for the once promising AIDS vaccine that was yanked from trial in South Africa last month after a sister vaccine being tested on humans throughout North America showed it may well increase risk of infection.

Researchers said at a conference in Seattle today that the germ appears to weaken immunity, causing more of the some 3,000 test subject who were given the vaccine to develop HIV than those who were given a placebo.

South African AIDS researchers have begun contacting the hundreds of volunteers who took part in the trials over recent months, warning them the vaccine could well make them more, not less, likely to contract the virus.

The move comes on the heels of an announcement last month by Merck Co. that an AIDS vaccine they were developing possibly caused more infections than it averted.

Of those given the vaccine, 19 contracted the virus as opposed to just 11 who were given the placebo.

“This is my worst nightmare,” Glenda Gray, the lead South Africa investigator for the vaccine study, told the Washington Times.

“I haven’t slept for days. I have a headache. I’m ready to resign from trials for the rest of my life.”

According to the Seattle Times, researchers in Capetown began contacting the more than 800 participants in the study on Tuesday, most of them via text messaging.

The goal, which researchers are calling an “unblinding” of the trial, is to let each of the participants know whether they were given a vaccine or a placebo.

While researchers say that the vaccine could not have caused HIV infection, it is possible the vaccine caused changes in the immune system which would make the virus easier to contract during later infection.

The US Merck vaccine trials took place in 15 cities including Boston, Los Angeles and New York.

Around the world, studies in Peru, Haiti and Australia were also conducted.

According to a spokesperson for Merck, most of the U.S. volunteers were gay men.

Ross von Metzke

© 2007 GayWired.com; All Rights Reserved