The study involved 20,583 women, aged 15-26, who were randomly assigned the quadrivalent HPV vaccine, the HPV16 component of the vaccine or placebo.
Over three years, the women underwent Papanicolaou testing with colposcopy or biopsy if abnormalities were detected.
Among the 17,129 women who tested negative for HPV 16/18, the vaccine had an efficacy of 99 per cent for preventing HPV16/18-related cancerous cervical lesions.
In an intention-to-treat analysis of all women, the vaccine had an efficacy of 44 per cent.
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