Changes in sexual behaviour among women in studies evaluating the dapivirine vaginal ring for HIV prevention

Researchers: Kudzai Hlahla,  Moni Neradilek,Morgan Garcia, Felix Mhlanga, Thesla Palanee-Phillips, Krishnaveni Reddy, Nishanta Singh, Carolyne A. Akello, Samantha Siva,  Leila E. Mansoor, Cindy E. Jacobson, Brenda Gati, Jennifer E. Balkus.

 August 2026

What Is The Study About?

Access to novel HIV prevention technologies often raise concerns of risk compensation. This analysis examined changes in the sexual behaviours of MTN 020/ASPIRE participants, a placebo-controlled randomised control trial, who subsequently enrolled in MTN-025/HOPE, an open-label extension using the dapivirine vaginal ring.

Why Is This Important?

Despite the decline in the incidence of HIV globally, countries in sub-Saharan Africa continue to bear the brunt of the epidemic, accounting for more than half of all new HIV infections in 2024. In the same year, 37% of new HIV infections were in Southern and Eastern Africa, where 140,000 adolescent girls and young women (AGYW) aged 15–24 years acquired HIV in this region. African AGYW are notably disproportionately affected by the HIV epidemic, as they are three times more likely to acquire HIV than their male counterparts, accounting for 63% of all new infections in the region. As such, the successful development of antiretroviral-based HIV prevention methods has been hailed as a critical step in HIV prevention. Pre-exposure prophylaxis (PrEP) in the form of pills containing tenofovir and emtricitabine, injectable cabotegravir and lenacapavir, and the dapivirine vaginal ring (DVR) have been shown to be safe and effective HIV prevention intervention tools. However, the introduction of these methods comes with the concern of potential risk compensation from key stakeholders, such as clinicians and policymakers.

What We Know…

Defined as an increase in behaviours that may increase the likelihood of transmission of sexually transmitted infections (STI), including HIV, in response to a reduction in the perceived level of risk or increased sense of protection, risk compensation has been studied in various health-related domains, including sexual health. Observational and randomised controlled trials (RCT) exploring risk compensation around HIV prevention methods in various populations have yielded mixed results. To our knowledge, risk compensation has not been studied in African women who have transitioned from an RCT evaluating the effectiveness of an HIV prevention tool, to a follow-up, open-label extension study (OLE) where participants were aware of the efficacy of the study product.

What Was Discovered…

The analysis involved data from women who participated in an HIV prevention trial assessing the effectiveness of the DVR (ASPIRE) and who subsequently transitioned to participate in an OLE study (HOPE), with full knowledge of the effectiveness of the DVR. We found that a greater proportion of women reported sex with a nonprimary partner during the OLE than during the blinded study (ASPIRE). Reported condom use was generally similar across studies during the follow-up period.

Sex with a nonprimary partner was reported more frequently in the HOPE than in the ASPIRE cohort during follow-up visits. This finding contrasts with the findings of studies involving tenofovir and emtricitabine as oral PrEP, in which the prevalence of sex with a nonprimary partner decreased or remained constant over time. Systematic reviews and meta-analyses evaluating PrEP use among people with a high likelihood of exposure to HIV have shown no change or an actual decrease in the reported number of sexual partners when comparing data at baseline versus follow-up visits. Data from the Partners PrEP trial, in which participants’ sexual behaviour was analyzed pre- and post-unblinding to determine whether knowledge of PrEP efficacy changed sexual risk behaviour, showed a slight increase in sex with an outside additional partner post-unblinding, with a statistically significant increase in condomless sex with nonprimary partners.

An increase in the frequency of sex with a nonprimary partner in the HOPE study could be attributed to risk homeostasis theory. When enrolled in HOPE, women might alter their perceived risk compared with when they were in ASPIRE, in light of the known efficacy of the DVR, to a level of acceptable risk they are willing to take, adjusting their behaviour accordingly, resulting in increased frequency of sex with a nonprimary partner. Additionally, the increase in reported frequency of sex with a nonprimary partner could reflect reporting bias that is often seen with continued study participation. Under-reporting of sexual behaviour that is considered socially undesirable or risky is common for women enrolled in HIV prevention trials. However, prolonged study participation due to transitioning to the open label extension could result in higher reporting rates of sexual behaviour as women become more comfortable with the product, procedures such as the CASI and build rapport with study staff, resulting in a decrease in pressure for social desirability. Despite being protected from HIV acquisition by oral PrEP or DVR, as in our case, such adjustments in behaviour; for example, increasing the number of sexual partners, could result in increased STI transmission due to the overlapping transmission pathways of HIV and other STIs if other prevention efforts are not undertaken. Studies and reports of individuals with a high likelihood of exposure to HIV have shown an association between the use of PrEP and increased STI incidence and recurrence.

This highlights the need to incorporate assessment of risk and risk perception in HIV risk reduction counselling and PrEP initiation, as well as further research on the economic and social drivers that may affect PrEP uptake, continued use, and associated changes in sexual behaviour. The continued and increased condom use observed in HOPE could also be due to the comprehensive risk reduction package that women received in both trials, which included risk reduction counselling and HIV testing. 

The Future/ Possible Solutions…

We found moderate evidence of risk compensation, as indicated by an increase in sex with a nonprimary partner, although without a significant change in self-reported condom use, during the HOPE study, where women were aware of the efficacy of the DVR. Understanding if and how sexual behaviours change with the use of PrEP products, such as the DVR, is important for the development of integrated PrEP and STI programmes tailored to the needs of women in sub-Saharan Africa. There is a need for continued efforts to provide a patient-centred, comprehensive risk reduction package, including condom promotion, health education and counselling, and HIV testing, in addition to various PrEP products, thereby giving women choices and empowering them regarding their sexual reproductive health.