Another HIV vaccine fails a trial in South Africa, disappointing researchers

In another setback in the long quest to prevent HIV infection, a trial in South Africa has been shut down because an experimental vaccine was not working, federal health officials announced Monday.

The trial, which began in 2016, followed one in Thailand that ended in 2009. That vaccine offered only modest protection against infection. Experts argued over how much, but the vaccine was no more than 30% protective.

Nonetheless, it was the only vaccine that had appeared to work at all.

“We hoped this vaccine candidate would work — regrettably, it does not,” said Dr. Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, which conducted the trial.

A vaccine against HIV, the virus that causes AIDS, is sorely needed. Even now, nearly 40 years after the start of the epidemic, 1.7 million people are newly infected each year — most of them in Africa, especially southern Africa, according to UNAIDS, the United Nations’ AIDS-fighting agency.

The trial — known as HVTN 702 but nicknamed Uhambo, which means “journey” in Zulu — included 5,407 young adult men and women in South Africa.

Last month, a safety-monitoring panel looked at early results and found there were 123 infections among participants who got a placebo injection and 129 among those who got the vaccine.

That clearly indicated that the vaccine was not protective but did not mean it was making participants more vulnerable to HIV, scientists said.