HIV Conference | The new challenges of prophylaxis

This Sunday July 23 opens in Australia on the 12^e International AIDS Society (IAS) HIV Congress. The successes of prophylaxis in the rich countries extend to the poor countries… but also lead to other problems.

Pre-exposure prophylaxis (PrEP) involves taking anti-HIV drugs before having risky unprotected sex, such as with strangers.

“In most pre-exposure prophylaxis programs, between a quarter and half of patients give up before a year,” explains Chase Cannon, an infectious disease specialist from the University of Washington who will give a conference in Australia. “The risks of HIV infection in the months following abandonment are very high. »

PrEP is at the heart of the 12^e HIV Congress. Researchers are trying to extend it to poor countries, for example by giving it to young adolescent girls in sub-Saharan Africa to reduce the risk of being infected during their first sexual relationship.

Currently, PrEP requires medication to be taken every day. Trials of long-term PrEP, in the form of an injection protecting six months, are underway. This would eliminate the need to return to the clinic or pharmacy often.

“At the moment, long-acting PrEP only works for two months,” says Jean-Pierre Routy, an HIV specialist at McGill University who will participate in a panel on immunotherapy and monoclonal antibodies at the IAS conference.

“Afterwards, there is a drop in white blood cells. So the tests will be redone with lower doses. A solution must be found, because the phenomenon of PrEP fatigue is very real. People think they’re hip and hot and healthy, so they have a hard time taking pills every day. »

Morality and condom

The contribution of PrEP to the recent increase in sexually transmitted infections (STIs), which is felt more in men than in women, raises debates. “With PrEP, the word “condom” no longer exists, image the D^r Routy. It should at least be worn with a stranger, even if it means taking it off if we see it again. PrEP protects against HIV, but not against venereal disease. It’s the equivalent of fixing a road to make it safer: people tend to drive faster afterwards. That’s why we see all kinds of PrEP trials for STIs, or post-exposure prophylaxis (PEP). »

In April, a Californian study published in the New England Journal of Medicine (NEJM) has confirmed that the antibiotic doxycycline reduces the risk of contracting an STI by more than 60% if taken within 72 hours of having unprotected sex with a stranger. This result is even better than those of a French study, IPERGAY, unveiled in 2018.

“I think doxy-PEP should be adopted as standard treatment,” says Anne Luetkemeyer of the University of California, San Francisco, lead author of the NEJM study. The D^r Routy points out that in Montreal, doctors are already prescribing doxy-PEP.

For his part, the D^r Cannon doubts that PrEP is responsible for the rise in STI rates.

Another conference speaker, anthropologist Ryan Whitacre of the University of California at Berkeley, studies “emerging sexualities”. “It’s clear that PrEP has sparked a lot of creativity in sexual experimentation. This has led to a rise in moralizing discourse on the pursuit of pleasure. Mr. Whitacre also does not believe that PrEP is responsible for the rise in STIs.

Pandemic

Another important part of the IAS conference is on monoclonal antibodies. “Their success against COVID-19 has taken this sector to great strides,” says Dr.^r Routy. Injectable monoclonal antibodies seem to be able to control HIV for several months, without any other treatment. And we can think of them as PrEP. The problem is that you need different monoclonal antibodies for different strains of HIV. So, that introduces a need to characterize the virus, which constitutes a brake. »

Last year at the IAS International AIDS Conference in Montreal, many hopes were pinned on an HIV vaccine based on the messenger RNA technology used in Moderna and Pfizer’s COVID-19 vaccines. “There may be an announcement in Australia,” says the D^r Routy. But now, “we talk less about mRNA vaccines against HIV”.