HIV trial’s failure a disheartening defeat
An SA test to probe the effectiveness of an experimental vaccine is halted after a review finds it offers no protection from the illness
To beat HIV the world will need a vaccine, expert after expert said after the announcement that a $104m HIV vaccine trial, the closest the medical fraternity has come to an actual drug, had failed.
Scientists this week halted the SA trial that was testing the vaccine after a review found it to be ineffective.
"I was catatonic," trial head Glenda Gray told a journalist, describing the moment she learnt the trial she had been running in SA had to be stopped.
The Boksburg-born doctor, mother and former HIV activist has spent the past few years working late into the nights (because of working hours in a US time zone) with fellow trial head US scientist Larry Corey, while residing in Cape Town, where she is president of the SA Medical Research Council.
The vaccine used in the SA trial, named HVTN 702, had reduced infections by a third in what is called the Thai trial, which was run by the US military between 2003 and 2006. Gray tells the FM that in the Thai trial the vaccine activated specific T-cells in the immune system. It was decided to boost the vaccine to further stimulate the same immune response that had been effective against HIV in some Thai people. Over 18 months, local participants got six vaccines, including extra immune boosters.
The data safety and monitoring board that checks trial data found last month that of the 2,694 South Africans who got the vaccine, 129 were infected with HIV, and of the 2,689 participants who received the placebo, 123 were.
It would have been less disappointing if the vaccine offered some protection instead of none, says the US National Institutes of Health’s Dr Anthony Fauci.
Preliminary trials show the vaccine activated the immune system to fight HIV.
However, but this didn’t prevent the disease.
Gray says the immune response may have been too weak to cope with the multiple exposures South Africans face — 14 times more than HIV exposures in Thailand.
Additionally, the HI virus mutates and replicates fast and has an outer surface called an envelope that is "impenetrable", making it impossible for the immune system to kill it, she says.