The vaccine trial in PrEPVacc
PrEPVacc’s vaccine trial will test whether two experimental combination vaccine regimens can provide any protection against HIV in populations at risk of acquiring HIV.
One regimen combines DNA with protein based vaccine, and the other combines DNA, MVA and protein based vaccine.
Both have already been evaluated in clinical trials in US, Europe and Africa and have demonstrated their safety and ability to induce immune responses.
The outcome of PrEPVacc will tell us whether the regimens can protect against HIV infection. PrEPVacc is the first HIV vaccine efficacy trial to be funded outside the US.
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In December 2023, the study announced that it had stopped further vaccinations as there is little or no chance of the trial demonstrating vaccine efficacy in preventing HIV acquisition.
The full results of the vaccine trial will not be known until all the study visits have been completed, which the study teams aim to do by June 2024. Full results will be analysed and shared with participants, study teams and the public in the second half of 2024.
The oral PrEP component of the study is continuing to completion.
About the Vaccine trial
Why now?
It is a pioneering time for HIV vaccine development, with other combination regimens being tested in large-scale trials (including the recently-stopped HVTN 705 'Imbokodo' and HVTN 702 ‘Uhambo’) in Africa.
PrEPVacc is complementary to these other efficacy trials as it is evaluating a combination of different vaccine candidates and regimens.
The two regimens that will be trialled in PrEPVacc have both already been evaluated in multiple phase I/II clinical trials in US, Europe and Africa and have demonstrated their safety and ability to induce immune responses.
We do not know whether either combination will work to prevent HIV infection, and the outcome of the large PrEPVacc study will tell us whether they can or not
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In December 2023, the study announced that it had stopped further vaccinations as there is little or no chance of the trial demonstrating vaccine efficacy in preventing HIV acquisition.
The full results of the vaccine trial will not be known until all the study visits have been completed, which the study teams aim to do by June 2024. Full results will be analysed and shared with participants, study teams and the public in the second half of 2024.
What are the vaccine combinations?
The two vaccine combinations are:
1) DNA with protein based vaccine (DNA-HIV-PT123 + monomeric AIDSVAX®B/E)
2) DNA, MVA and protein based vaccine (DNA-HIV-PT123 + trimeric CN54gp140, followed by poxvirus-based MVA CMDR + trimeric CN54gp140)
It is absolutely NOT POSSIBLE to get HIV infections from the vaccines used in this study.
Two of the vaccines contain pieces of man made HIV DNA which tell the body to make small amounts of proteins that look like the ones found in HIV. These are ‘DNA-HIV-PT123’ and ‘MVA CMDR’ respectively.
The two other vaccines are made of man made proteins which are similar to proteins from the outer surface of HIV. These are called ‘AIDSVAX’ and ‘CN54gp140’. To help the body notice and respond to these proteins, they are combined with substances known as adjuvants.
There is also a placebo in PrEPVacc that does not contain vaccine. The placebo for the study vaccines will be a sterile liquid called saline, which is the salty water used to rehydrate people.