HIV vaccine trials offer a ray of hope

2015-06-14 16:57

An HIV vaccine that has the potential to end the Aids epidemic in South Africa is currently being tested in six sites countrywide.

If all goes well in the follow-up trials set to begin late next year, the vaccine could be available for general use by 2019.

More than 250 people have been enrolled in the trial (of HVTN 100) that began in January and is expected to be completed by the end of this year. It is being conducted by the HIV Vaccine Trial Network and the Medical Research Council.

Participants have been given a modified version of the so-called Thai vaccine to test it for safety and ascertain whether the medicinal regimen induces the predicted immune system response.

The Thai – or RV144 – vaccine made headlines worldwide in 2009 when there was evidence that it could offer protection against HIV infection by up to 31% when tested in Thailand. The findings were hailed as a breakthrough in the decades-long struggle to develop an effective vaccine.

The vaccine had to be tested as part of confirmatory trials in various parts of the world.

South Africa tested it in 2013 to see whether South Africans would have the same immune response to RV144 as that witnessed in Thailand. Trials were conducted at three sites (Soweto, Klerksdorp and Cape Town).

The reason for testing the immune response instead of its effectiveness in HIV-infection prevention is physiological aspects such as gender, age, ethnicity and body mass index often affect individual responses. Women, for instance, respond better to vaccines than men, while heavy drinkers and obese people don’t respond as well.

The results of the 2013 South African trial, HVTN 097, were pleasing. The immune response of South Africans was as good, if not better, than that of the Thais, despite differences in ethnicity and high levels of obesity in the 100 people who participated in the local study.

This set the wheels in motion for the first phase of the trial currently under way, said Professor Linda-Gail Bekker of the Desmond Tutu HIV Centre at the Institute of Infectious Disease and Molecular Medicine in the faculty of health sciences at the University of Cape Town.

Speaking on the sidelines of the seventh South African Aids conference in Durban last week, Bekker said the findings of the HVTN 097 trial, which were released in November last year, were the best news South Africa had received in a while when it came to HIV-prevention research.

“It’s too early to tell what the outcome of HVTN 100 will be, but we are hoping to more than match the immune response noticed in the HVTN 097 trial. If we do, we will forge ahead and conduct phase-two trials where we will test the effectiveness of the vaccine. Phase two will be a large study that will include other African countries.”

The vaccine currently being tested had been modified to include different proteins that would target the HIV strain that was most prevalent in South Africa.

Bekker explained: “The vaccine that was used in our previous trial was targeted at strains E and B, which are prevalent in Thailand. The vaccine we are testing now targets clade C, a strain that is prevalent in South Africa.”

The results of the trial are expected early next year.

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January 20 2019