HIV vaccine trial test fails in South Africa

SA deaths not linked to Covid-19 vaccines - Sahpra

On Tuesday, researchers in a trial vaccine for the Human Immunodeficiency Virus (HIV) in Africa, announced it has been shut down after data showed the jabs only gave limited protection against the virus.

The vaccine failed to provide sufficient protection against HIV to young women in sub-Sahara Africa who accounted for a large number of infections in 2020 in the continent.

The vaccine which is produced by Johnson & Johnson (J&J), was however, found to be safe with no serious side effects reported.

According to a report in the New York Times, J&J said the study will not continue based on the efficacy data.

Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases (NIAID), said of the vaccine,  “Although this is certainly not the study outcome for which we had hoped, we must apply the knowledge learned from the … trial and continue our efforts to find a vaccine that will be protective against HIV”.

The Trial

The vaccine is based on an adenovirus called Ad26, modified to carry fragments of four H.I.V. subtypes into the body in hopes of provoking an immune response that might defend against infection.

The trial, known as Imbokodo, tested an experimental vaccine in 2,600 young women deemed at high risk of H.I.V. infection in five sub-Saharan African countries.

Two initial shots and two boosters over the course of a year, were given to participants in the trial which began in 2017. Researchers tracked the numbers of new infections in the placebo and vaccine groups from the seventh month (one month after the third vaccination) through the 24th month.

Over two years, 63 of 1,109 participants who received the placebo were infected with H.I.V., compared with 51 of 1,079 participants who received the vaccine, giving the vaccine an efficacy rate of 25 per cent.

Earlier studies, including one carried out in Thailand, had indicated that the kind of antibodies this vaccine provoked might be sufficient to offer good protection from H.I.V. for at least an initial period of time.

The principal investigator of the trial and chair of the South African Medical Research Council, Glenda Gray, said “But in South Africa, the higher rates of H.I.V. incidence means you need something much more potent”.

“When the disappointing data showed a low efficacy rate, guidelines set up before the trial dictated it should be shut down.

“A vaccine that offered only 25 per cent protection risked giving women a false sense of security”.

Vaccine setbacks

This is the latest setback in the attempts to develop a vaccine to combat the virus, which had infected over 37 million people globally as of 2020.

Last year, another trial was aborted after a different experimental vaccine failed to offer sufficient protection.

Future experiments

Going forward, researchers may have to adopt new approaches.

Moderna has said that it would test a vaccine based on the mRNA platform used to devise the company’s coronavirus vaccine

Johnson & Johnson company said a parallel trial, known as Mosaico that uses a different iteration of this vaccine will continue. It is being tested on men who have sex with men and transgender people, in eight countries including Poland, Brazil and the United States.

Mosaico, is testing the vaccine against different subtypes of H.I.V. in different populations, and could produce different efficacy results.

The lesson from the failed trial lies in figuring out why it worked for the 25 per cent of people who were protected and not for the others, and then trying to translate those clues into a recipe for a future vaccine, Gray said.

Author: Greg