Efficacy of a carrageenan gel in increasing clearance of anal HPV infections in men: interim analysis of a double-blind randomized controlled trial.

Pre-clinical studies demonstrated carrageenan's anti-human papillomavirus (HPV) activity. We assessed efficacy of a carrageenan-based gel compared to a placebo gel in increasing the clearance of anal HPV infections among gay, bisexual, and other men who have sex with men (gbMSM). Of 255 enrolled gbMSM, 134 were HPV-positive at baseline and had valid HPV results for ≥2 visits. Carrageenan did not differ from placebo in clearing all baseline infections (HR=0.84, 95% CI: 0.31-2.27), based on having two consecutive HPV-negative visits following at least one HPV-positive. There were no remarkable differences for analyses at the HPV-type level or by HIV status.