After 40 years of research, still no AIDS vaccine exists on the market. With the RNA technology used against Covid-19, a solution could be developed. However, in those 40 years, we have lost sight of the people living with AIDS, and that must definitely change.
Over the past 40 years, nearly 32 million people have died from AIDS, a disease resulting from a weakened immune system caused by HIV* infection. To date, seven vaccines have been tested against the retrovirus (see inset). But the most promising vaccine, tested in Thailand a decade ago, was effective in protecting only 31% of people against HIV. The main obstacle to tackling HIV is the development of neutralising antibodies. “These antibodies only appear several years after HIV infection and in only 10% of patients,” explains the American physician and immunologist Barton Ford Haynes in a recent article published in the scientific journal, Nature. “However, for Covid-19, antibodies develop 10 days after infection or two weeks after vaccination.”
“The rapid development of the Covid-19 vaccine was facilitated due to the nature of the situation,” says Matthieu Perreau, associate professor with the Immunology and Allergy Service at Lausanne University Hospital (CHUV). “Everything moved quickly because the research had learnt lessons from SARS** and MERS***. But also because new vaccine strategies were ready, thanks especially to HIV research.”
Once developed, a vaccine has to go through a series of essential hoops before it can be approved by medical authorities. First of all, its safety (i.e., absence of harm), then its immunogenicity (its ability to induce an immune response), and finally its efficacy (ability to prevent the onset of disease caused by infection) must be proved. “The problem with the HIV vaccine is the difficulty in generating an appropriate immune response.”
Another major difference between the HIV virus and Covid-19 is the appearance of the emergence of variants. Covid-19 variants are not completely resistant to vaccine protection. But HIV mutates so rapidly that it can escape immune system pressure within a couple of weeks.
There are now a variety of HIVs, subdivided into a complex nomenclature system of types, subtypes, and strains (groups formed by a specific organism and its progeny) of HIV. An HIV vaccine therefore has the complex task of protecting against such diversity. Making matters worse, HIV can persist in the body a few days after infection by hiding in certain cells, which then act as a reservoir for the virus. This means that HIV can not only resist immune system pressure but also antiretroviral treatment. “The HIV vaccine must also strike fast and hard to keep this reservoir from forming,” Matthieu Perreau says.
The stigmatisation and discrimination of people living with HIV has since been the subject of extensive research. To peel back preconceived notions and discuss progress on the issue, David Jackson-Perry, a special advisor at the CHUV’s Infectious Diseases Consultation Unit, works on a daily basis with people living with HIV and their loved ones. He points out the U = U rule, which stands for Undetectable=Untransmittable. In other words, a person undergoing treatment has a viral load that is undetectable and therefore cannot transmit the virus. However, a recent study by the UK-based non-governmental organisation National AIDS Trust showed that only 4% of the population believe that. These people can also hope for life expectancy and quality of life comparable to those of the general population. But David Jackson-Perry says that unfortunately, “representations in the media are harder to change.
It’s still a very taboo subject. These days, you don’t see films or television series about people living with HIV.”
These outdated notions cause people to act inappropriately. David Jackson-Perry cites the example of a patient hospitalised for another illness, and the healthcare professional asks in front of other patients, “So, have you taken your antiretrovirals?” Or the physiotherapist who sees a patient with back pain and is informed – for no apparent reason – that the patient is living with HIV, then puts on gloves before treating the patient.
We must remain optimistic. “I’m convinced that one day we’ll find an HIV vaccine. It could come through education about the immune system and the sequential administration of different vaccines. That could force the immune system to generate highly effective neutralising antibodies.”
The expert believes that messenger RNA (mRNA) vaccines, such as Covid-19 vaccines, might offer hope. “Using them could allow for repeated administration without loss of immunogenicity.” By definition, mRNA vaccines do not generate a response against the vector, because there is no vector. “So in theory you can administer it as many times as you need. It’s a completely new approach.” The first trial of an mRNA vaccine against HIV was launched in the summer of 2021 by the US company Moderna (see inset).
The stalling in the search for an HIV vaccine could also be due to the negative image that has long stuck to the disease. “We started talking about AIDS in 1981, but US President Ronald Reagan waited four years to use the word in public,” David Jackson-Perry reminds us. The reason it took so long, he says, is that “the people that most commonly caught the virus come from communities that were already stigmatised.” They were memorably coined as the “4-Hs”, for homosexuals, heroin addicts, Haitians and haemophiliacs, not to mention sex workers. “The fact that there is still no AIDS vaccine is also because politicians have never done anything about it.” /
* Human Immunodeficiency Virus
** La pandémie du syndrome respiratoire aigu sévère (SRAS) est apparue en Chine en 2002.
*** Le syndrome respiratoire du Moyen-Orient (MERS)
a été découvert en 2012. C’est une forme de coronavirus qui provoque une pneumonie aiguë.
Matthieu Perreau discusses the obstacles to developing an HIV vaccine. He is associate professor with the Immunology and Allergy Service at Lausanne University Hospital (CHUV/UNIL).
Retroviruses can integrate their genome into the host genome. The AIDS virus can therefore express itself via the host cell throughout its life. This process allows the virus to multiply within the body and weakens the individual’s immune system. Their immune system is deficient, and they can no longer fight other viruses they catch.
The AIDS virus was first identified in monkeys in the Congo region in the early 20th century and was transmitted to humans around 1950. In the ensuing decades, the virus and its variants migrated throughout the world. In 2020, 37.7 million people were living with HIV worldwide, including 1.7 million people infected with the virus within the previous year. Since the beginning of the AIDS epidemic, 36.3 million people have lost their lives to the disease.
The American biotech firm Moderna, now known for its Covid-19 messenger RNA vaccine, plans to use the same technology against HIV. The vaccine provides cells with the genetic code for HIV proteins. The immune system can then recognise them and produce antibodies to fight the virus if infected. Moderna has recently launched a study expected to produce final results by 2023.