A phase 2 clinical trial of an experimental HIV vaccine being conducted in sub-Saharan Africa has just been halted, with data highlighting that the injections only offered limited protection against the virus. This new failure testifies once again to the complexity of this pathogenic agent which continues to challenge modern medicine.
The pharmaceutical giant Johnson &Johnson has just announced the end of its phase 2 clinical trial of its latest vaccine candidate against the human immunodeficiency virus (HIV) , the latter not offering sufficient protection against AIDS. The serum, whose development was funded by Johnson &Johnson, the Bill &Melinda Gates Foundation and the National Institutes of Health, was based on an adenovirus called Ad26 .
The pathogen had been modified to carry fragments of four HIV subtypes into the body in hopes of eliciting an immune response against future infections.
During this trial, which began in 2017, dubbed Imbokodo, the experimental vaccine was administered to 2,600 young women deemed to be at high risk of HIV infection in five countries around the world. 'Sub-Saharan Africa. This sample represents nearly two-thirds of new HIV infections in the region.
Participants received two initial injections and two booster doses over the course of a year. The researchers then analyzed the number of new infections in the sample and in a placebo group between the seventh month (one month after the third dose) and the 24th month.
During this time frame, 63 of the 1,109 participants who received the placebo became infected with HIV, compared to 51 of the 1,079 participants who received the vaccine, which which gives an efficiency rate of 25% . For the authors, this was insufficient and even potentially dangerous. A vaccine that only offers 25% protection risked giving women a “false sense of security” “, underlines to Times Glenda Gray, the principal researcher of the test.
Unfortunately, this is not the last battle lost against this virus which, still in 2020, would have infected more than 1.5 million people additional.
Another trial was also interrupted last year in South Africa due to lack of efficacy. "I should be used to it by now, but you're never used to it, you always put your heart and soul into it “, argues Dr. Gray. The researcher, who is also president of the South African Medical Research Council, has indeed been working on the development of an HIV vaccine for more than fifteen years.
In the meantime, other battles are brewing. According to Johnson &Johnson, a parallel trial relying on a different iteration of this latest vaccine is currently ongoing. It is being tested on men who have sex with men and transgender people in eight countries.
Moderna, which distinguished itself with its mRNA vaccine against the SARS-CoV-2 coronavirus. has just announced the launch of human tests for an HIV vaccine based on the same technology. This first stage will take place over two years. It will involve 56 HIV-negative volunteers between the ages of 18 and 50.
