HIV vaccine trial in South Africa fails

Drug appears to work only 30 percent of time

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 percent 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 S. 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. A difference of just six infections in so large a pool of participants could have been due to chance.

The Uhambo vaccine had to be significantly changed from the one tested in Thailand because South Africa has a different dominant strain of HIV.

The vaccine used canarypox, a bird virus that can infect human cells but cannot multiply in them, to deliver into the body a protein found on the outer envelope of HIV The immune system learns to recognize the protein and to make protective antibodies to it.

Two other HIV vaccine trials, Nos. 705 and 706, known as Imbokodo and Mosaico, are still underway.

Both use a common cold virus as the vector and different surface proteins.

SCHALK VAN ZUYDAM/ASSOCIATED PRESS FILE PHOTO Pharmacist Mary Chindanyika looks at documents on a fridge containing a trial vaccine against HIV in 2016 on the outskirts of Cape Town, South Africa. The latest attempt at an HIV vaccine has failed.