To evaluate the efficacy of a carrageenan-based lubricant gel in reducing the risk of genital HPV infections among young sexually active women.
Between January 2013 and December 2016, 258 women aged 18 years and older were randomly assigned (1:1) to a carrageenan or a placebo lubricant gel. Participants were asked to self-apply the gel every other day for the first month and prior to and following each intercourse during the entire 1-year study period. Sociodemographic, behavioral and sexual history data were collected using computer-assisted self-administered questionnaires. We used Roche’s Linear Array assay to detect and genotype HPV DNA in self-collected vaginal samples. HPV types were categorized according to phylogenetic grouping based on tissue tropism and oncogenicity (alphapapillomavirus subgenus 1, 2 and 3). The primary outcome was the incidence of a newly detected infection i.e. an infection by an HPV type that was not present at baseline. We computed hazard ratios (HR) and 95% confidence intervals (CI) using univariate Cox models considering the first occurrence of a new infection in each participant. We also used a mixed effect survival-time model to accommodate the correlated data structure and multiplicity of HPV types to which participants were exposed.
The median age was 22.7 years (range 18.0-45.2) and the median follow-up time was 7.6 months (range: 0-25.3) completed over up to 7 visits (mean: 4.8, median: 5). Baseline characteristics including age, ethnicity, age at first intercourse, number of lifetime sex partners, number of partners in the last month, HPV vaccination status and HPV status were well balanced between arms. 40 participants in the carrageenan arm and 59 participants in the placebo arm got infected by at least one new HPV type. The HR for the first occurrence of a new infection was 0.59 (95% CI: 0.39-0.88). A lower incidence was consistently observed for all alphapapillomavirus subgenera (HR range: 0.44-0.61). When considering all new HPV types acquired by each participant (not only the first infection), 89 infections occurred in the carrageenan arm versus 152, in the placebo arm. The HR was 0.45 (95% CI: 0.27-0.76) taking into account correlated data.
Although preliminary and based on interim analysis, our trial suggests that the use of a carrageenan-based lubricant gel can reduce the risk of new genital HPV infections, irrespective of taxonomic grouping.