Sustained efficacy and immunogenicity of the HPV-16/18 AS04-adjuvanted vaccine up to 7.3 years in young adult women.

We report efficacy and immunogenicity of the HPV-16/18 AS04-adjuvanted vaccine up to 7.3 years post-vaccination. The study was conducted in a population (N=433) of women enrolled in Brazilian centres from an initial placebo-controlled study. Women were aged 15-25 years at first vaccination. During the most recent year of follow-up, approximately 7 years after initial vaccination, no cases of infection or cytohistological lesions associated with HPV-16/18 were observed in the vaccinees. Vaccine efficacy (95% confidence interval) up to 7.3 years was 94.5% (82.9, 98.9) for incident infection, 100% (55.7, 100) for 12-month persistent infection and 100% (-129.8, 100) for cervical intraepithelial neoplasia grade 2+. Antibody titres for total IgG and neutralising antibodies remained several folds above natural infection levels and >or=96% of women were seropositive. Vaccine safety was similar to placebo. This is the longest follow-up study for a licensed cervical cancer vaccine.