For the two decades that Moses Nsubuga, a local artiste commonly known as Supercharger, has been taking anti-retroviral drugs (ARVs), his biggest worry has been the toll the drugs could take on his health.

"Every day I take seven tablets. I worry that one day the medication will affect my liver or kidney,” said the artiste-turned HIV activist.

Having developed resistance to the first line medication, Supercharger is now on second line drugs.

People on first line medication take one or two pills.

His hope is to see an HIV vaccine developed during his lifetime that could prevent those who are not infected from getting the disease, and also to address the burden of taking pills every day — for those already living with the virus.

Despite advances in prevention and treatment research, HIV/Aids is still a public health threat for many countries especially in sub-Saharan Africa.

The United Nations Joint Programme on HIV/Aids (UNAids) estimates that globally, 36.7 million people were living with HIV in 2016. Of these, about 20.9 million were on antiretroviral therapy.

Improvements in antiretroviral therapies over the years has meant that apart from keeping people healthy, the drugs are also being used as a form of prevention.

People who are on treatment and have their viral load suppressed are less likely to transmit the virus to their sexual partners.

The use of condoms, medical male circumcision and pre-exposure prophylaxis are also among the prevention strategies being promoted.

But even with these interventions in place, experts believe HIV will be hard to eliminate without a vaccine.

"When you look back at the epidemics we have had in the past such as smallpox, measles and polio, we have not been able to control them without a vaccine,” said Prof Pontiano Kaleebu, the director of the Uganda Virus Research Institute, which conducted the first HIV vaccine trial in Africa in 1999.

New infections

According to UNAids, about 1.8 million people get newly infected with the HIV virus every year, mostly in sub-Saharan Africa.

In East Africa, new infections range from 52,000 in Uganda to 100,000 in Kenya annually. Numerous vaccine trials have been carried out in different countries across the world, yet none has yielded the results that the scientists hope could be a game changer.

"Many of the vaccine trials we have had in the past start with a lot of promise in animals. Then we go into phase one and two and realise the immune response they are inducing is not strong enough to prevent HIV infection,” said Dr Francis Kiweewa, the head of research and scientific affairs at the Makerere University Walter Reed project.

Out of about 40 clinical trials that have been undertaken globally so far, Dr Kiweewa said just five were able to reach phase III, and all except the trial conducted in Thailand showed promise.

Test vaccine

The Thailand trial called RV144 showed that volunteers who got the test vaccine were 31 per cent less likely to acquire HIV during the trial period compared with those who did not receive the vaccine.

Although a 31 per cent less risk of infection was not sufficient enough, Dr Kiweewa said the current vaccines being tested have been developed based on the Thailand concept.

Uganda, Tanzania, Mozambique and South Africa will soon be part of a large-scale efficacy trial called PrEPVacc, which will use a combination of DNA and the Thai study.

According to Prof Kaleebu, another challenge facing vaccine development is the diverse nature of the HIV viruses, which is complicated when they recombine in the body.

People who have recombinant HIV viruses often tend to progress faster to diseases compared with those without.

Dr Kiweewa said that despite commitments made by African governments to invest at least two per cent of their GDP on research, many have faltered.

Except for South Africa, which has invested heavily in HIV research, much of the work on the virus in high burden countries is being funded through external donations.

With four phase III vaccine trials currently ongoing in South Africa, the Americas and Europe, the scientists see promise despite the challenges.

"In fact, this is the first time we have up to four trials going on at the same time that have reached phase three. It is exciting news for us,” said Dr Kiweewa.

The results of these trials are expected between 2020 and 2021.

Agencies