Risk of Delayed Human Papillomavirus Vaccination in Inner-City Adolescent Women.

BACKGROUND: Uptake of human papillomavirus (HPV) vaccine in the United States is slow, and the effectiveness of the vaccine has not been assessed in high-risk adolescent populations. METHODS: We conducted a longitudinal study of 1139 sexually active, inner-city adolescent women receiving the 3-dose quadrivalent (4vHPV) vaccine. Cervical and anal specimens collected semiannually were tested using an L1-specific polymerase chain reaction assay. Postvaccination incidence of 4vHPV vaccine and nonvaccine HPV types, and risk of cervical cytological abnormalities, were assessed in relation to time to completion of all 3 vaccine doses. RESULTS: Compared to vaccine naive women at enrollment, vaccinated women had significantly lower incidence rate ratios of cervical infection with HPV6/11/16/18 (0.2; 95% confidence interval [CI], .1-.4) and the related types HPV31 and HPV45 (0.4 [95% CI, .2-1.0] and 0.3 [95% CI, .1-.6], respectively), as well as significantly lower incidence rate ratios of anal infection with HPV6/11/16/18 (0.4; 95% CI, .2-.7). Notably, we observed higher risks of cervical HPV6/11/16/18 infection (hazards ratio [HR], 2.9; 95% CI, 1.0-8.0) and associated cytological abnormalities (HR, 4.5; 95% CI, .7-26.0) among women immunized at ≥15 years of age who took ≥12 months (vs <12 months) to complete the 3-dose regimen. CONCLUSIONS: Among adolescents immunized at ≥15 years of age, a longer time to complete the 3-dose schedule was associated with an increased risk of anogenital HPV6/11/16/18 infection and an increased incidence of associated cervical cytological abnormalities.