Picture: 123RF/GAMJAI
Picture: 123RF/GAMJAI

Johnson & Johnson (J&J) has stopped a mid-stage test of its HIV vaccine in Southern Africa after the shot showed insufficient ability to protect people from contracting the virus. 

The trial, called Imbokodo, showed the vaccine was just 25% effective in preventing HIV infection over a period of two years, short of a goal of 50% efficacy, according to a statement. A similar vaccine developed by the drugmaker will continue being tested in Europe and the Americas in a final-stage study called Mosaico, said Paul Stoffels, J&J’s chief scientific officer. 

The study’s halt is another setback in efforts to control HIV, a treatable yet potentially lethal disease that afflicts almost 38-million people worldwide. About 1.5-million were infected last year. While people can live healthy lives with the virus, prevention with a vaccine still appears tantalisingly out of reach. 

“With vaccines, it looks very difficult to do,” Stoffels said in an interview. “The virus integrates almost immediately into the body and it’s very difficult to create immune protection.”

That African study enrolled about 2,600 women in five countries in the southern part of the continent, where HIV infection is extremely common and is often spread by heterosexual contact. Imbokodo began enrolling participants in 2017, focusing on women at high risk of HIV.  

Protecting women from HIV infection “continues to be a huge global priority”, said Mitchell Warren, executive director of Avac, an HIV vaccine advocacy organisation. “Seeing that this product isn’t going to be a viable option for women at risk is a disappointment.”

J&J’s work on an HIV vaccine has been encouraging, Warren said, as it is the first major drugmaker in the field to make major progress since Merck’s trial of a promising shot failed almost 15 years ago. The success of J&J’s adenovirus-based technology in its Ebola and Covid-19 vaccines also boded well, he said. 

Cold virus

J&J’s HIV vaccine uses a cold virus that has been altered to raise an immune response against the virus that causes Aids. Participants received a total of four shots, two of the vaccine and two booster shots containing HIV proteins that were hoped would further sharpen the immune response. 

The study goal of 50% efficacy was set at a level that could “change the future of the HIV pandemic”, Stoffels said. “You won’t get that with 25%.”

However, the second study of the related vaccine will go on, as it is sufficiently different that it still stands a chance of success, Stoffels said.

The Mosaico study enrolled a male and transgender population where the spread of HIV is less intense and transmission patterns are different. The patients receive six shots of a vaccine regime that has a slightly broader spectrum, he said. 

Despite the setback, Stoffels said he’s optimistic that the limited efficacy of the vaccine can help scientists advance towards a treatment that’s more effective. Study participants’ immune responses will be analysed to better understand why some were protected and others were not, he said. 

HIV vaccine disappointments stretch back almost to the initial discovery of the disease in humans. Margaret Heckler, who at the time was the US health & human services secretary, said in 1984 that a shot to prevent HIV would be ready for testing within two years. Researchers have chased the goal ever since.

Bloomberg News. More stories like this are available on bloomberg.com

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