Extended Follow-up of Women Who Received One, Two, and Three Doses of the HPV Vaccine in the Costa Rica Vaccine Trial (CVT), ESCUDDO-CVT Study

PRIMARY OBJECTIVES: I. Estimate the change in antibody levels between years 11 and 20. II. Estimate the proportion of individuals who become seronegative (i.e.: serorevert) between years 11 and 20. SECONDARY OBJECTIVES: I. Assess the prevalence and distribution of type-specific HPV infections at least 18 years after HPV vaccination. II. Assess the number and type of premalignant lesions present at least 18 years after vaccination. III. For each dose regimen, characterize HPV-specific memory B cells and long-lived plasma cells present at least 18 years after HPV vaccination, and compare these characteristics with results from earlier time points. OUTLINE: This is an observational study. Patients complete a short questionnaire regarding risk factors for HPV infection and undergo collection of blood samples for testing HPV16 and HPV18 levels on study.