Cervical infection with vaccine-associated human papillomavirus (hpv) genotypes as a predictor of acquisition and clearance of other hpv infections

Abstract

Background. Recent birth cohorts vaccinated against human papillomavirus (HPV) may be protected against up to 4 genotypes (HPV-6,-11,-16, and-18). If natural competition exists between these and other HPV types, then the prevalence of other types may increase after vaccination. Methods. Cohort information from3 studies was used to compare acquisition and clearance of 30 different HPV types (individually and grouped by species), according to infection status with vaccine-targeted types at baseline and the time of the index infection, respectively. Hazard ratios (HRs) were adjusted for predictors of multiple-type infection. Results. Among 3200 females across all studies, 857 were infected with HPV at baseline, and 994 acquired new infections during follow-up. Females infected with HPV-16 were at higher risk of acquiring other ?-9 HPV types (HR, 1.9; 95% confidence interval [CI], 1.2-3.0) but at similar risk of clearing existing ?-9 HPV infections (HR, 0.9; 95% CI, .7-1.3). Females infected with vaccinetargeted types were generally at higher risk of acquiring additional types (HRs, > 1.0) and at equal risk of clearing existing infections. Accounting for multiple comparisons, none of the HRs of < 1.0 or >1.0 were statistically significant in our analyses of acquisition or clearance. Conclusions. Vaccine-targeted HPV types do not appear to compete with other types, suggesting that HPV type replacement is unlikely to occur.