“Our paper, which was specifically designed to evaluate whether condoms can offer protection against HPV infection, is the first to show a significant protective effect of condoms in preventing male-to-female HPV transmission.”

While condoms are highly effective in reducing genital transmission of human immunodeficiency virus, the extent to which they protect against other sexually transmitted infections, including human papillomavirus (HPV), has been unclear. In fact, several previous studies had failed to show a protective effect of condoms in preventing male-to-female transmission of HPV. Our paper, which was specifically designed to evaluate whether condoms can offer protection against HPV infection, is the first to show a significant protective effect of condoms in preventing male-to-female HPV transmission. This information is important for creating accurate public health messages about condom use.

  Does it describe a new discovery or a new methodology that’s useful to others?

Unlike previous studies, our study was specifically designed to evaluate whether condoms can prevent male-to-female transmission of HPV. By following women who were HPV-negative at enrollment (a longitudinal study design), we were able to evaluate a cause-and-effect relationship between condom use and HPV infection.

Many previous studies have been cross-sectional in design, meaning they evaluated condom use and HPV infection at only one point in time. This can be misleading, because it is not possible to establish a temporal sequence (i.e., you might measure condom use in the past six months, but the HPV infection you detect may have been acquired a year ago; therefore, the study design doesn’t allow you to determine whether condoms protect against acquiring HPV infections).

Furthermore, we used a Web-based sexual behavior diary to capture daily information on sexual behaviors, including condom use. By asking women to complete these diaries every two weeks, we were able to collect very detailed data on condom use, and improve the accuracy of our data. We also studied a cohort of women who first reported sex with a male partner within two weeks of enrollment or during the study. HPV infections are very common in sexually active young women and they are often detected transiently (meaning they may no longer be detectable after a period of time); therefore, these restrictions helped to ensure that the study population would be susceptible to new infections, and that the infections that we detected were indeed new infections.

  Could you summarize the significance of your paper in layman’s terms?

We found that condoms offered women significant protection against HPV infections when they were used consistently. Women who used condoms for all sex acts in the eight months prior to HPV testing were 70% less likely to acquire a new HPV infection than women who used condoms less than 5% of the time, and even women who used condoms at least half the time were half as likely to acquire a new infection (compared with women who used condoms less than 5% of the time). This was after taking into account how many new partners the woman had had over the past eight months, and how many previous partners she believed her male partners to have had.

  How did you become involved in this research and were there successes or failures?

I became involved in this research during my graduate studies in epidemiology at the University of Washington. The project was part of my Ph.D. dissertation. Laura Koutsky, Ph.D., a professor of epidemiology at the University of Washington, was the principal investigator of the study. She had been studying the natural history of HPV infections in university-aged women, and was interested in specifically addressing the question of whether condoms are protective against HPV infections.

  Where do you see your research leading in the future?

With more data, we plan to look at whether condoms also protect against HPV-related pre-cancerous lesions. Furthermore, with the recent availability of a prophylactic HPV vaccine, we are interested in developing research projects to monitor the individual-level and population-level impacts of vaccination programs, as well as projects to characterize the natural history of HPV infections in less-studied populations, including older women, adolescent and young men, and immunocompromised populations.

  Are there any social or political implications of your research?

The information that condoms reduce male-to-female transmission of HPV is critical for developing accurate public health messages about the effectiveness of condoms in preventing the spread of sexually transmitted infections. Furthermore, even with the recent availability of a prophylactic HPV vaccine (which offers protection against two cancer-causing strains of HPV), consistent condom use can help prevent transmission of other cancer-causing HPV strains. It is important to stress, however, that women continue regular Pap smear screening, regardless of whether they are vaccinated and use condoms.