Uganda volunteers in phase III of HIV vaccine efficacy trials

Monday December 21 2020

Scientists work on HIV tests at Kemri laboratories, Nairobi. PHOTO | EVANS HABIL

By The EastAfrican

Uganda has enrolled its first volunteer participants in a large trial to study whether two new vaccines offer protection against HIV.

The African-led PrEPVacc study will be testing two experimental combination vaccines on populations that are most at risk of getting infected with human immunodeficiency virus (HIV) to see whether the drugs provides any protection.

Ugandan scientists Wednesday launched the third phase of the HIV vaccine efficacy trials in the central district of Masaka, the Ministry of Health said.

The study is combining evaluation of experimental HIV vaccines and pre-exposure prophylaxis (PrEP) concurrently. PrEPVacc will test whether a new form of oral PrEP, TAF/FTC (Descovy) taken daily, is equivalent or more effective than TDF/FTC (Truvada) taken daily, in the context of the current PrEP availability situation at the five study sites in four countries: in Masaka, Uganda; Mbeya and Dar-es-Salaam, Tanzania; Maputo, Mozambique, and Durban, South Africa.

The two vaccines have been tested for safety in previous clinical trials in Africa, Europe, and the US. The study is being funded by the European and Developing Countries Clinical Trials Partnership, supported by the EU.

“PrEPVacc provides two great opportunities: first, for Africans to participate and lead in the first HIV prevention trial to test two ways to prevent HIV,” said Prof Pontiano Kaleebu, the PrEPVacc chief investigator.  “Second, an opportunity to grow the capacity of African sites to do future trials themselves,” he said.



The five-year PrEPVacc project will run from January 2018 to March 2023. Preparation for the trial includes a registration cohort (an observational study), whose first participants were enrolled in July 2018. The first participants in the clinical trial enrolled in December 2020.

According to the PrEpVacc website, PrEPVacc is seeking a minimum of 1,668 participants, men, and women aged 18-40 years.

Participants will be from the general and key populations who report behaviours that put them at increased risk of catching HIV. This may include female bar workers, commercial sex workers, fisherfolk, and men who have sex with men.

Studies have shown that PrEP using the daily anti-HIV medicine Truvada can provide near-perfect protection against HIV when taken carefully during periods of risk.

“In PrEPVacc we are testing Truvada PrEP against a new medicine, Descovy PrEP. Participants will be offered PrEP during the vaccine immunisation phase (from week 0 to 26 in order to prevent HIV.  This will give the vaccines the best possible chance of working,” the scientists said.

Participants enrolled in PrEPVacc are however not obliged to take PrEP, but they will be encouraged to use it as an HIV prevention option, the scientists added.

“Among those that decline it, PrEPVacc researchers will try to find out what the barriers to acceptance are,” they noted.

In the PrEPVacc’s vaccine trial, two experimental combination vaccine regimens will be tested to ascertain whether they can provide any protection against HIV. One regimen combines DNA with a protein-based vaccine, and the other combines DNA, MVA, and a protein-based vaccine. Modified Vaccinia virus Ankara (MVA) is licensed as a third-generation vaccine against smallpox and serves as a potent vector system for development of new candidate vaccines against infectious diseases and cancer.