• Potential conflict of interest: Nothing to report.


We appreciate Dr. Halfon's interest in our study. As highlighted by the study title and conclusions regarding counseling messages,[1] our study specifically addresses monogamous heterosexual couples and not other populations such as human immunodeficiency virus (HIV)-infected men who have sex with men (MSM). As Dr. Halfon notes, our study provides a quantitative assessment of sexual activities to further support the counseling messages. Among heterosexual partnerships, couples reported having vaginal sex a median of 12 times per month; 65% had sex during menses, 30% had anal sex, and the majority indicated that regular use of condoms was infrequent. Importantly, we found no specific sexual practices associated with hepatitis C virus (HCV) transmission risk but acknowledge that the low rate of HCV infection among partners limited our ability to detect such associations. The comments by Dr. Halfon regarding the risks of anal sex are largely drawn from MSM and HIV-infected persons, which represent a very different group with respect to risk from anal sex practices and other factors potentially influencing the risk of HCV transmission. As we have previously highlighted, sexual transmission of HCV likely requires special circumstances, such as a disrupted genital mucosa, the presence of bacteria or other viruses, and/or an altered mucosal immunity. Anal sex or the presence of a sexually transmitted disease may represent one of those “special” circumstances, but in the setting of HIV-infected MSM, other factors (including those related to HIV infection) may be equally or more important. A case report of possible anal transmission in a heterosexual couple[2] does not provide sufficient epidemiological evidence to draw conclusions regarding the risk of anal sex for the population of heterosexual couples.

In conclusion, recommendations for HIV-infected MSM cannot be generalized to HIV-uninfected heterosexual couples. HCV transmission by sex in monogamous heterosexual couples is a rare event, no specific sexual practices have been identified that may increase that risk, and thus no evidence-based recommendations regarding use of condoms with anal sex or sex during menses can be made. However, we believe that counseling messages regarding risks of sexual transmission should be individualized, including consideration of condom use as a means of reducing the already very low risk of HCV transmission to zero.




  • 1Division of Gastroenterology, University of California, San Francisco, San Francisco, CA

  • 2Division of Infectious Diseasesm University of Texas Medical Branch, Galveston, TX