Hope of an effective Human Immuno-deficiency Virus (HIV) vaccine may have been dashed, as researchers announced Tuesday that an advanced trial in Africa had been stopped after data showed that the shots offered only limited protection against the disease.
The therapy, by Johnson & Johnson, is one in a long line found to offer little defence against the virus. A particular candidate vaccine even increased the risk of infection.
Another trial was halted last year in South Africa after a different experimental vaccine failed to offer sufficient protection. Some 1.5 million people were infected with HIV worldwide in 2020, and 38 million are living with the ailment.
Scientists were dismayed by the most recent failure.
The principal investigator and chair of the South African Medical Research Council, Dr. Glenda Gray, said: “I should be used to it by now, but you’ve never used to it – you still put your heart and soul into it.”
She has been working to develop a treatment for more than 15 years
Entirely, new approaches might be needed. This month, Moderna announced that it would test a vaccine based on the mRNA platform to devise the company’s COVID-19 vaccine.
Named Imbokodo, the trial tested an experimental vaccine on 2,600 most predisposed HIV young women in five sub-Saharan African nations, as the gender accounted for almost two-thirds of new infections in the region last year.
Johnson & Johnson, Bill and Melinda Gates Foundation, and the United States National Institutes of Health-funded the exercise.
The vaccine relied on an adenovirus called Ad26, modified to carry fragments of four HIV subtypes into the body in the hope of provoking an immune response that could guard against infection.
Participants in the Imbokodo trial, which began in 2017, were given two initial shots and two boosters in a period of one year. Researchers tracked the number of new infections in the placebo and vaccine groups from the seventh month (a month after the third vaccination) through the 24th month.
Over two years, 63 of 1,109 partakers, who received the placebo, were infected with HIV, compared with 51 of 1,079 participants that received the vaccine – giving the therapy an efficacy rate of 25 per cent.
Earlier studies, including one carried out in Thailand, had indicated that the kind of antibodies the vaccine provoked might be sufficient to offer good protection from the sickness for an initial period of time.
But a parallel trial that uses a different iteration of this vaccine will continue, Johnson & Johnson said. It is being tested on men, who have sex with men and transgender people, in eight countries, including Poland, Brazil, and the United States.
The study, labelled Mosaico, is testing the vaccine against different subtypes of HIV in different populations and could produce different efficacy results.