By Bunmi Yekini
Women who take drugs to prevent HIV infection do not engage in riskier sexual behaviour or face higher rates of other sexually transmitted infections (STIs), according to a study conducted in western Kenya.
Health officials have long feared that the use of HIV prevention medication could lead to risk compensation, a situation in which individuals feel protected enough to take greater sexual risks, potentially fuelling a rise in infections such as gonorrhoea and syphilis. Those concerns intensified last month after Kenya introduced Lenacapavir, a long-acting injectable HIV prevention drug administered once every six months.
However, new research conducted in the lakeside city of Kisumu suggests the fears may be largely unfounded. The study tracked about 650 women for 12 months, ending in February 2024. About 60% of the participants used oral pre-exposure prophylaxis (PrEP), medication taken to prevent HIV infection, while the rest did not take the drug.
Findings published this week in the journal PLOS Medicine showed that women who used PrEP did not report more condomless sex and were not more likely to contract other sexually transmitted infections compared with those who did not use the medication.
“During the 12 months of follow-up, there was no association between frequency of condomless sex at the last sex and PrEP use consistency through six months,” the researchers wrote in the report titled “Oral preexposure prophylaxis use and the risk of bacterial sexually transmitted infections and HIV among African women.”
The study also found no evidence linking PrEP use to increased STI risk among women considered to be at elevated risk of HIV infection. In total, STIs were detected in 12 women who used PrEP consistently, 17 women who used it inconsistently, and 25 women who did not use PrEP at all. The research team included scientists from Kenyatta National Hospital, the University of Washington, the Fred Hutchinson Cancer Center and McGill University in Canada.
Participants were recruited from family planning clinics and were considered to be at substantial risk of HIV infection. All were offered PrEP pills as part of the study, but only about 390 women, roughly 60% of the group, agreed to start the medication.
Throughout the year-long follow-up, the participants underwent regular testing for HIV as well as bacterial STIs including chlamydia and gonorrhoea. Researchers found that STI infection rates were nearly identical among women who used PrEP and those who did not, suggesting that the preventive medication itself did not increase the likelihood of contracting other infections.
The findings address a long-standing debate in public health about whether HIV prevention methods might unintentionally encourage risky sexual behaviour.
Scientists have often warned about the possibility of risk compensation, in which people who believe they are protected against HIV might be less likely to use condoms or adopt other safe-sex practices.
But the study indicates that women who use PrEP may actually be more cautious because they already recognise their vulnerability to HIV and other infections.
In addition, PrEP users often receive regular counselling and health monitoring during medical visits related to the medication, which could reinforce safer sexual behaviour.
Researchers also highlighted the strong effectiveness of PrEP in preventing HIV infection.
Only four women in the study contracted HIV during the 12-month follow-up period. Three of those infections occurred among women who had declined to start PrEP.
“No HIV infection occurred in women reporting consistent PrEP use, but 75% of all new HIV infections occurred in women who declined to initiate PrEP, representing a tragic missed opportunity for HIV prevention,” the researchers said.
PrEP works by introducing antiretroviral medication into the bloodstream before exposure to HIV. If the virus enters the body, the drugs prevent it from establishing infection. When taken consistently, PrEP pills can reduce the risk of acquiring HIV by more than 90%, according to health experts.
Kenya’s National AIDS and STIs Control Programme last month introduced lenacapavir, a long-acting injectable version of PrEP designed to provide protection against HIV for six months at a time.
The injection was first rolled out in Nairobi on Feb. 26 and will expand to other regions in phases. Migori and Busia counties are scheduled to launch the programme on March 12, followed by Siaya and Mombasa on March 13, and then Homa Bay.
Additional rollouts are planned for Machakos, Nakuru, Kilifi and Kakamega on March 26, with Kisii and Kajiado also expected to introduce the injection.
Public health experts say long-acting HIV prevention methods could significantly improve uptake and adherence by removing the challenge of remembering to take daily pills.
They believe the availability of injectable options such as lenacapavir could help expand HIV prevention efforts, particularly among populations at higher risk of infection.