Cape Town – Experts have reassured the public that despite results showing more participants who received a trial HIV vaccine injection recorded a positive HIV diagnoses compared to those
given placebo treatment, it does not mean that the vaccine regimen caused HIV.
Last week it was announced that one of South Africa’s biggest HIV vaccine efficacy studies, HVTN 702/Uhambo, had been stopped early. This after an independent data and safety monitoring board (DSMB) found the regimen was not effective in preventing HIV.
Uhambo was the world’s first
HIV vaccine efficacy study and
was conducted in South Africa since 2009. The study enrolled 5407 HIV-negative participants at 14 sites across South Africa, consisting of sexually
active women and men aged 18 to 35 years.
Volunteers were randomly assigned to receive either the investigational vaccine regimen or placebo injections.
The DSMB examined data from 2694 volunteers who received the investigational vaccine regimen and 2689 volunteers who received the placebo injection, in an interim analysis on January 23.
A total of 129 HIV infections occurred among the vaccine
recipients, and 123 HIV infections occurred among the placebo recipients.
HVTN 702 co-chair and professor of medicine at the Desmond Tutu HIV Centre at UCT, Linda-Gail Bekker, said the variation in numbers was small and not significant.
“This occurred by chance and as related by the Data Safety board,
there is no worry of harm here,” she said.
On the standard of prevention that study participants had access to, Bekker said: “We follow the highest standard of prevention at all our sites: risk reduction counselling, access to condoms, regular testing, availability of partner counselling and testing, PrEP, PEP, referral for VMMC (voluntary medical male
circumcision), on site STI screening, testing and treatment, and on-site contraception.”
The study participants who acquired HIV were referred to ART (antiretroviral therapy) sites for treatment.
“It is important, because treatment is lifelong, that they establish care at a clinic of their choice. Where there are barriers to this, sites will assist the navigation to ART care.
“All are counselled at the time of diagnosis and again until treatment is established. If they cannot access care - then the HVTN has a fund to supply ARVs short term to tide individuals over.”
Regarding behaviour of participants possibly changing as a result of being part of the trial, Bekker explained that part of the informed consent process was to be very clear about prevention misconception and to reiterate this throughout the study period.
“Everyone who is enrolled is checked to ensure they get this and PrEP and condoms are offered at
every visit for this reason as well,” she said.
This was a unique set of vaccine components and did not have any implications for other trials or participants, Bekker added.
“We did have high hopes for this regimen given its results in Thailand and so we are disappointed and have suffered a blow.
“The high incidence demonstrated in this trial particularly among young women, reinforces that we need to continue to strengthen our prevention approach and find more effective ways to reduce transmission urgently.
"A quest for an effective vaccine is part of that and should continue with gusto and urgency,” Bekker said.