Theresa Rossouw is a UP professor of immunology, and has been treating patients living with HIV and researching the body’s response to the virus for more than two decades. She outlines the importance of World AIDS Vaccine Day, also known as HIV Vaccine Awareness Day.

World AIDS Vaccine Day, also known as HIV Vaccine Awareness Day, is observed annually on 18 May.  HIV vaccine advocates mark the day by promoting the continued urgent need for a vaccine to prevent HIV infection and AIDS.

They acknowledge and thank the thousands of volunteers, community members, health professionals, supporters and scientists who are working together to find a safe and effective AIDS vaccine, and urge the international community to recognise the importance of investing in new technologies as a critical element of a comprehensive response to the HIV/AIDS epidemic.

Imagine if we had the means to prevent HIV infection. Imagine if we could have prevented 86 million infections and saved 40 million lives over the past 40 years. Imagine if people such as Freddie Mercury, Arthur Ashe and Nkosi Johnson, who radically transformed music, sport and social justice respectively, could still be with us today. Imagine if the four million South Africans who were parents, loved ones or children to so many of us could have been saved.

There is hardly a household that has not been touched by the devastating toll of HIV infection. And, after more than four decades, it continues to ravage families and communities. With 1.3 million new infections and roughly 630 000 deaths in 2022, there are currently about 39 million people living with HIV in the world. Of these, about 8 million live in South Africa.

Even though antiretroviral treatment (ART) strategies have come a long way, they are limited by late diagnosis, the need for lifelong treatment and the ever-present threat of drug resistance.[1] Getting people to start and stay on treatment is also challenging. Globally, and in South Africa, treatment coverage is only 75%. In other words, one in every four people living with HIV is not on treatment. In South Africa, about half of the two million people not on treatment are believed to have been on ART before and to have disengaged from care.[2]

Prevention of HIV infection is equally challenging. In South Africa, male condom distribution decreased by 45% between 2018 and 2022, coupled by a resurgence in sexually transmitted infections.[3] This drastically increases the risk of acquiring HIV infection. Access to pre-exposure prophylaxis of HIV is also still limited and plagued by many of the same challenges as treatment.   

The reality is that viral pandemics can only be ended by an effective vaccine. Take smallpox as an example, a disease that was eradicated from the globe as a result of a vaccine. While not all viruses can be stopped as effectively, vaccines still prevent many infections and deaths. By exposing the body to tiny bits of a virus, vaccines help the immune system to make protective responses, such as antibodies, which kick into action as soon as the body encounters the real threat.

A good example is the COVID-19 vaccine. During the pandemic, more than two billion people were fully vaccinated and an estimated 2.4 million deaths prevented within the first eight months of 2021.[4] In the US, scientists estimate that COVID-19 vaccines had prevented at least 1 million deaths, 10 million hospitalisations and 36 million SARS-CoV-2 infections by the end of November 2021.[5] 

On HIV Vaccine Awareness Day, it is important to reflect on the necessity to develop a safe and effective vaccine. An important consideration is why, in contrast to COVID-19, an HIV vaccine remains elusive. There are three main reasons: the shapeshifting nature of the virus, which prevents an effective immune attack; the ability of HIV to integrate into a host’s genetic code and hide away from the immune system; and the inability of current vaccines to elicit the kind of immune response that can eliminate such a formidable foe.

But recent advances in technology might have brought us closer to overcoming these challenges. New preventive vaccines strategies have changed the way in which the tiny bits of HIV are delivered to the immune system. The first innovation is the use of messenger RNA (mRNA), a concept popularised by the COVID-19 vaccines, although it has been in development for decades. Since the process of creating mRNA vaccines does not require cell culture or animal material, the vaccine products can be developed within weeks or months. It also seems as if these kinds of vaccines can produce more robust immune responses.

Another preventive vaccine uses a weakened form of cytomegalovirus (CMV) to deliver the virus. This delivery system makes sense, because CMV infection is a very common, lifelong infection that does not cause symptoms in the vast majority of people. This means that it should be able to safely deliver and help the body retain the HIV vaccine material for a long period. This constant stimulation is exactly what is needed to prevent the immune system from forgetting about the virus.  

These vaccines are given to people who do not have HIV infection. But scientists are also working on therapeutic vaccines for people living with the virus. The aim of these vaccines is to improve the body’s immune response to HIV to slow down the disease process. The hope is that these vaccines could eventually lead to long-term remission of the infection or even a cure.

This HIV Vaccine Awareness Day, let us allow ourselves to imagine a world without HIV. It can be done – we must not stop fighting.