(Chicago Tribune) –After decades of shadowboxing with the human immunodeficiency virus, researchers were encouraged four years ago when a test of a vaccine on 16,000 people in Thailand turned up a previously unknown vulnerability in the resilient pathogen.
The vaccine was only 31 percent effective and wore off over time, so it could not be approved for use in a general population. But the study’s results allowed scientists to exploit the chink in HIV’s armor, reformulate the drug and bring it back for another clinical trial.
Now all eyes are on South Africa, where researchers will begin inoculating thousands of volunteers Monday in the latest – and, some say, most promising – effort to develop a vaccine that prevents the disease. It is only the seventh full-scale human trial for a virus that infects more than 2 million people and kills more than 1 million every year.
“If this study shows efficacy . . . this would be a tectonic, historic event for HIV,” said Nelson L. Michael, director of the U.S. Military HIV Research Program, which led the Thailand study.
Should the vaccine prove to be 50 percent to 60 percent effective, experts say, that would be sufficient for drugmakers Sanofi Pasteur and GSK to begin licensing negotiations with the South African government. While such a rate is well below the acceptable margin for other vaccines, it would still make this one worth producing here – given that nearly 1 in 5 people are infected.
And an agent that works in South Africa could be adjusted later for use against viral subtypes that circulate elsewhere, including in the United States.
“Given that right now we have nothing, we’d be happy if this vaccine were even 45 or 50 percent effective,” said Gita Ramjee, director of the HIV Prevention Research Unit at the Medical Research Council in Durban, which is running two of the 15 trial sites. “Even a modestly effective vaccine like that would have a huge impact here.”
About 5,400 people – who must be HIV-negative, sexually active and between the ages of 18 and 35 – are being recruited. Each will receive five injections over the course of the year and then be monitored for two years.
Half the volunteers will receive a placebo so that researchers can measure the vaccine’s efficacy. But that hasn’t deterred South Africans from signing up. Few lives are untouched by the disease.
“I don’t want another generation to go through what I did,” said Thembi Dlamini, 29, who this week was being screened at a clinic for participation in the trial.
Her older sister died of AIDS five years ago in a brutal descent. The only silver lining was its brevity: She was gone in just three months, with a stash of HIV medication in her dresser drawer. Her shame was greater than the fear of wasting away.
Dlamini estimates that half her friends are HIV-positive – hardly an outlandish calculation in a country where about a third of the women in her age group have the virus.