This study is extending follow up of women who participated in the Costa Rica Vaccine Trial (CVT) and received one dose or two doses of the human papillomavirus (HPV) vaccine, along with a group of women who received three doses. It also studies the stability of HPV defenses in these groups of women for up to 20 years after initial vaccination. Studying samples of blood in the laboratory may provide information on how long one, two, and three doses of the vaccine provide protection against HPV. The results of this study may also help researchers learn whether one dose of HPV vaccine is enough to protect against HPV.
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Seropositivity
Timeframe: Up to 20 years after initial vaccination
Change in antibody levels
Timeframe: Between years 11 and 20 after initial vaccination
Proportion of individuals who serorevert
Timeframe: Between years 11 and 20 after initial vaccination