A new study suggests that people who are HIV negative in a heterosexual relationship with an HIV-positive partner do not demonstrate a significant increase in sexual risk-taking, even when they are protected against HIV transmission with prophylactic drugs.

A team of international researchers, led by Dr. Jared Baeten of the University of Washington, Seattle, analyzed the data of more than 3,000 participants from the Partners PrEP study.

In 2011, the Partners PrEP study found that pre-exposure prophylaxis could protect HIV-negative men and women in serodiscordant couples (when one partner is HIV positive) from HIV transmission.

For their study, published in The Lancet Infectious Diseases, the researchers wanted to determine whether an HIV-negative partner who had the knowledge that they were protected against HIV transmission would demonstrate any changes in sexual behavior.

The researchers analyzed the study participants for up to 12 months before the protective effects of pre-exposure prophylaxis were shown in the study, and 12 months after, once the study participants were told of the protective effects.

As well as receiving the protective drugs, the participants also underwent risk-reduction counseling, safety monitoring, pregnancy testing, and testing for gonorrhea, chlamydia and trichomoniasis.

Results of the study showed that after the study participants were told of the effectiveness of pre-exposure prophylaxis, there was no significant difference in the level of unprotected sex between partners.

The researchers note that prior to revealing the results of the drug trials, participants were reporting a decrease in the frequency of unprotected sex. This suggests that risk counseling and other measures could have been effective.

However, this finding did not change after the participants were made aware of the protection of pre-exposure prophylaxis from HIV transmission.

Dr. Baeten says:

To our knowledge, this study provides the first empirical data on sexual behavior in heterosexual people receiving open-label oral pre-exposure prophylaxis for HIV prevention.

The results provide encouraging evidence that behavioral changes as a result of pre-exposure prophylaxis might not undermine its strong HIV prevention and public health benefits.”

In a comment piece linked to the study, Kristen Underhill of the Yale Center for Interdisciplinary Research on AIDS at Yale Law School and Kenneth H. Mayer of the Beth Israel Deaconess Medical Center at Harvard Medical School, say that further studies are needed to determine the behaviors of pre-exposure prophylaxis users:

“Future research should examine the behaviors of pre-exposure prophylaxis users outside trial settings, behavioral strategies for optimization of pre-exposure prophylaxis uptake and adherence while decreasing risk-taking, methods for assessment of users’ behaviors over time and methods for training providers.”

Additionally, they note that researchers and implementers should also investigate the context of behavior among users of the drug:

“Individuals might have personally meaningful reasons to take risks, such as fertility desires, and understanding these motivations can strengthen efforts to support pre-exposure prophylaxis users before, during, and after use.”

Medical News Today recently reported on the development of an insertable ring that could prevent HIV in women.