It appears likely long-acting injections of PrEP, administered by a health professional every couple of months, will become a reality after several studies have indicated their efficacy at preventing HIV transmission. That said, clinical trials are still ongoing, so it’s not a possibility just yet.
However, one study published this month has taken available data to estimate how PrEP injections may help reduce HIV transmission amongst gay and bi men.
The study, published in the Journal of Infectious Diseases, estimated that if half the men currently taking PrEP in the southeastern US switched instead to having an injection, there would be a 4.3% reduction in HIV transmission over ten years.
That might not sound like a big difference, but bear in mind the study was looking at switching men already on PrEP to a different form of the medication. Taken as a daily tablet, PrEP is already known to be highly effective.
The small estimated benefit comes from the fact that some men are not great at sticking to a daily tablet regime. Furthermore, an injection is believed to offer longer-lasting partial protection after use is discontinued (whereas protection from daily pills decreases swiftly if you forget to take your dose for a couple of days).
The researchers say around 15% of men who have sex with men in the southeastern US take PrEP. If twice that number were encouraged to take the medication – either as tablets or as an injection – there could be a 17% reduction in HIV transmission over a similar ten-year period. They believe offering more options for how to take PrEP could lead to more people opting to take the medication.
“There is a lot of excitement about the various HIV prevention options in the research pipeline. Long-acting injectable (LAI) PrEP is likely to be the next innovation to become available to patients, so we wanted to model the potential impact on the HIV epidemic,” said researcher Kevin M. Maloney, an epidemiology PhD student at the Rollins School of Public Health at Emory University, to Healio.
“Our model did not target long-acting PrEP to the men who were designated to have low adherence to daily-oral PrEP,” Maloney said. “In the real world, there will be more nuanced decision-making, so we may see additional benefits if long-acting PrEP is used by patients who struggle with daily adherence to a pill.”
Maloney also said ensuring PrEP – as pills or injections – was as affordable as possible would help to further boost the numbers of those taking the medication.
According to the CDC, there were approximately 36,400 new HIV infections in the United States in 2018. This figure has fallen since the 1980s and 1990s, but has remained around the same level since 2014. Gay and bisexual men make up around two-thirds of that figure each year.
In 2019, President Trump pledged to eliminate HIV transmission in the US by 2030. Most HIV experts say greater access to PrEP is crucial in achieving this goal.