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Researchers announced Tuesday that the trial of an advanced HIV vaccine in Africa has been shut down after data showing that the vaccines offer only limited protection against the virus.
The vaccine made by Johnson & Johnson is one in a long line where it offers little defense against one of medicine’s most formidable enemies, HIV. One candidate vaccine even increased the risk of infection.
another try Stopped last year in South Africa after a different experimental vaccine failed to provide adequate protection. In 2020, around 1.5 million people worldwide were infected with HIV, and 38 million people live with the infection.
Scientists were horrified by the latest failure.
“I should have gotten used to it by now, but you never got used to it – you’re still putting your heart and soul into it,” said Glenda Gray, the trial’s principal investigator and chair of the South African Medical Research Council. Dr. Gray has been working on developing an HIV vaccine for over 15 years.
Completely new approaches may be needed. This month, Moderna announced that the company will test a vaccine based on the mRNA platform used to design the coronavirus vaccine.
The trial, called Imbokodo, tested an experimental vaccine in 2,600 young women thought to be at high risk of HIV infection in five sub-Saharan African countries. Women and girls were responsible for almost two-thirds of new HIV infections in the region last year.
The trial was funded by Johnson & Johnson, the Bill and Melinda Gates Foundation, and the National Institutes of Health.
The vaccine was based on an adenovirus called Ad26, which has been modified to carry parts of the four HIV subtypes into the body in hopes of inducing an immune response that can defend against infection.
Mitchell Warren, executive director of AVAC, an advocacy group lobbying for AIDS prevention and treatment, said amid excitement about new vaccine technologies, the cancellation of the trial was a “reality check”.
“It’s a great reminder that HIV is a pathogen unlike any other in its complexity,” he said. “We know the platform works, but what do we put in it? Because this virus completely infects the immune system that we are trying to boost with a vaccine.”
Participants in the Imbokodo trial, which began in 2017, were given two starter needles and two boosters for one year. Researchers tracked the number of new infections in the placebo and vaccine groups from month seven (one month after the third vaccination) to month 24.
Within two years, 63 of the 1,109 participants who received a placebo were infected with HIV, while 51 of the 1,079 participants who received the vaccine became HIV-infected, giving the vaccine an efficacy rate of 25 percent.
Previous studies, including those conducted in Thailand, have shown that the types of antibodies this vaccine triggers may be sufficient to provide good protection from HIV, at least for an initial period.
Dr. “But the high incidence of HIV in South Africa means you need something much stronger,” Gray said. “The induced immune responses were not sufficient to stop the high attack rates we saw in Africa.”
When disappointing data show a low efficacy rate, the guidelines created before the experiment dictates should be closed. Dr. A vaccine that only provides 25 percent protection risks giving women a “false sense of security,” Gray said.
However, Johnson & Johnson said a parallel trial using a different iteration of this vaccine will continue. It is being tested on men and men who have sex with transgender people in eight countries, including Poland, Brazil and the United States.
This study, called Mosaico, tests the vaccine against different HIV subtypes in different populations and may produce different efficacy results.
Dr. Gray said the lesson from the failed trial lies in why it works for 25 percent of protected people and doesn’t work for others, and then trying to translate those tips into a prescription for a future vaccine.
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