HIV vaccine candidate trialed in Sub-Saharan Africa falls short

An HIV vaccine candidate trialed in Sub-Saharan Africa offers no substantial protection against HIV infection among young women, the study organizers say.

According to a statement released this week (31 August) by Johnson & Johnson (J&J), the US drugmaker that produced the HIV vaccine candidate, the mid-stage Imbokodo study began in 2017, reached full enrollment in 2019 and completed vaccinations on 30 June 2020.

After 24 months of follow-up, 51 of 1,079 of participants who received the vaccine candidate acquired HIV compared with 63 of 1,109 who did not receive the vaccine candidate, showing vaccine efficacy of only 25.2 per cent.

Mitchell Warren, executive director of AVAC, global advocacy for HIV prevention, tells SciDev.Net the drug had shown "promising results in animal studies and earlier, smaller human trials".

Warren says that the idea was for Imbokodo vaccine to be at least 50 per cent effective, and that the final result was very disappointing.

The study involved women of ages 18 to 35 years old in Malawi, Mozambique, South Africa, Zambia and Zimbabwe, with participants receiving a total of four doses over 12 months.

Glenda Gray, head of the South African Medical Research Council (SAMRC), which helped to implement the Imbokodo study, agrees that the 25.2 per cent efficacy is too low to make the vaccine useful.

We continue to stand in solidarity with people living with and vulnerable to HIV, and remain committed to furthering our research against this devastating virus."

Paul Stoffels, J&J Chief Scientific Officer

SAMRC's Gray says that another trial with the vaccine, known as Ad26, is continuing in America and Europe using an optimized booster regime.

"This optimized booster gives higher and broader immune responses than the booster used in Imbokodo," Gray explains. "Study participants are men who have sex with men and transgender populations in North America, Latin America and Europe."

Oluwatosin Alaka, a senior programme officer at the New HIV Vaccine and Microbicide Advocacy Society in Nigeria, says that while Africa awaits a new HIV vaccine, this is the time for policymakers to sensitize Africans on the HIV prevention tools they could use before exposure, right at the point of HIV transmission and, after being infected with the virus.

"Those at high risk of acquiring the virus should use more than one option like PrEP [an HIV prevention medicine] and condoms," Alaka explains, adding that while PrEP helps to prevent HIV, it does not prevent one from getting pregnant nor does it protect one from contacting other sexually transmitted infections.