Death of Aids in sight
A trial of the only vaccine to offer partial protection from HIV, after 30 years of research, was started in South Africa this week.
The uhambo ('journey') study was announced at the SA Aids Conference in Durban, which ends today.
The leader of the study is Glenda Gray of the Wits perinatal HIV research unit.
The study, which will cost $125-million (about R1.28-billion), will take about 10 years to complete.
It is a "licensure study", meaning it is licensed to lead to the marketing of a medicine if successful.
Scientists have been searching for a vaccine to stop the spread of HIV since the 1980s, when the virus was discovered, said James Maynard, spokesman for the HIV Vaccine Trial Network.
"The only vaccine that offered some protection against HIV was discovered in a trial in Thailand in 2009," said Maynard.
It gave participants in the Thai study a 31% protection rate from the HI-virus after a year of treatment.
The same product will be used in the research in South Africa.
"This is it. The next big HIV vaccine preventative trial in the world is happening here in South Africa," Maynard said.
But it is highly possible that a usable vaccine will not emerge from the trial.
The vaccine will have to offer at least 50% or 60% protection to be given the green light for use, said Mitchell Warren, director of Avac, an HIV advocacy group.
In the Thai trial, the vaccine was shown to offer participants 60% protection from HIV within a year of their vaccination, but with time the protection rate dropped to 31%.
"The Thai government did not allow a vaccine to be produced [because of the] low protection rate," said Warren.
The South African trial will kick off with 100 HIV-negative participants in Soweto, Klerksdorp and Cape Town.
Researchers will firstly determine whether the vaccine is as effective when used on South Africans as it was in the Thai trials. From 2016 - if the vaccine proves to be effective - scientists hope to enrol thousands of HIV-negative trials participants.
They expect some results to be ready for publication by 2019.
Scientists say a vaccine is the only way to end the Aids epidemic.
Gray said the scientists involved in the trial would try to make the vaccine remain active in the body for longer and offer more protection from HIV.
But a vaccine that offers only some protection would still be important, Gray said.
"We currently only have imperfect methods to prevent HIV.
"A vaccine with partial effectiveness might work in conjunction with medical male circumcision and antiretrovirals as prevention."