Epidemiologic Evaluation of Human Papillomavirus Type Competition and the Potential for Type Replacement Post-Vaccination.

BACKGROUND: Millions of women have been vaccinated with one of two first-generation human papillomavirus (HPV) vaccines. Both vaccines remain in use and target two oncogenic types (HPVs 16 and 18); however, if these types naturally compete with others that are not targeted, type replacement may occur following reductions in the circulating prevalence of targeted types. To explore the potential for type replacement, we evaluated natural HPV type competition in unvaccinated females. METHODS: Valid HPV DNA typing information was available from five epidemiological studies conducted in Canada and Brazil (n = 14,685; enrollment across studies took place between1993 and 2010), which used similar consensus-primer PCR assays, capable of detecting up to 40 HPV types. A total of 38,088 cervicovaginal specimens were available for inclusion in our analyses evaluating HPV type-type interactions involving vaccine-targeted types (6, 11, 16, and 18), and infection with each of the other HPV types. RESULTS: Across the studies, the average age of participants ranged from 21.0 to 43.7 years. HPV16 was the most common type (prevalence range: 1.0% to 13.8%), and in general HPV types were more likely to be detected as part of a multiple infection than as single infections. In our analyses focusing on each of the vaccine-targeted HPV types separately, many significant positive associations were observed (particularly involving HPV16); however, we did not observe any statistically significant negative associations. CONCLUSIONS: Our findings suggest that natural HPV type competition does not exist, and that type replacement is unlikely to occur in vaccinated populations.

Safety and reactogenicity of a quadrivalent human papillomavirus (types 6, 11, 16, 18) L1 viral-like-particle vaccine in older adolescents and young adults.

BACKGROUND: Prophylactic vaccination with a quadrivalent HPV (types 6, 11, 16, 18) vaccine (qHPV) has been shown to prevent infection with HPV 6/11/16/18 and associated disease in women and more recently, in men. Here we report on the safety and reactogenicity of the qHPV vaccine in males. A total of 4,065 healthy males aged 16-26 years were enrolled into a randomized, placebo-controlled, double-blind trial. Subjects were randomized 1:1 to receive qHPV vaccine or placebo at day 1, month 2, and month 6. Safety and tolerability were assessed via the collection of reported adverse experiences (AEs). All serious AEs (vaccine- or procedure-related or not) and all deaths occurring during the study were recorded. Safety analyses were conducted in all subjects who received at least one dose of vaccine or placebo. The proportion of subjects who reported at least one injection-site AE was higher in the qHPV vaccine group versus the placebo group (60.1% vs 53.7%, respectively), however most of these AEs were mild/moderate in intensity. The incidence of at least one systemic AE was comparable between the vaccine and placebo groups (31.7% vs 31.4%, respectively). There were no vaccine-related serious AEs or deaths. The occurrence of AEs did not increase with each successive injection, and among trial participants who were seropositive for at least one vaccine HPV type at enrollment, the profile of adverse events was similar to that of the entire study cohort. The qHPV vaccine was generally well tolerated in males aged 16-26 years and had a favorable safety profile.