KAMPALA — A trial of an experimental HIV vaccine in Uganda, Tanzania and South Africa has been stopped early after preliminary data suggested it would not be effective in preventing infection, according to the trial's chief investigator.

The news is the latest blow to efforts to find an effective vaccine against a virus that has so far claimed about 40 million lives globally. Another 39 million are living with HIV, the majority of them in Africa.

The trial for the vaccine, part of a wider initiative called PrEPVacc, began in December 2020 with the enrolment of 1,512 healthy adults aged 18 to 40 and was due to end in 2024.

Pontiano Kaleebu, chief investigator for the programme, told Reuters on Thursday (Dec 7) the programme's independent data and safety monitoring committee had "recommended that even if we continue we will not be able to show that the vaccine can be effective".

While there are drugs that can reduce the risk of getting HIV and treatments that can control the virus and prevent people from developing Aids, the deadly immune condition resulting from untreated HIV, experts say an HIV vaccine would be an important tool in ending Aids as a public health threat.

The trial, led by African researchers with support from various European institutions like Imperial College London, was testing two different combinations of experimental HIV vaccines.

It was also testing a new form of oral pre-exposure prophylaxis (PrEP), a drug that reduces the risk of getting HIV, to see if it was as effective as existing drugs. That part of the trial is ongoing.

Participants were mostly drawn from populations at high risk of infection like sex workers, gay men and fishermen.

A statement released on Wednesday by the vaccine trial programme said the failed trial, which was the only remaining active HIV vaccine efficacy trial in the world, underscored "how challenging it is to develop an effective HIV vaccine".

Researchers in South Africa terminated another trial in 2020 after tests of a vaccine in more than 5,000 people failed to show benefits.

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Source: Reuters