Vaccines against oncogenic types of human papillomavirus (HPV) v placebo or no HPV vaccine to prevent vaccine-type HPV-associated cervical cancer precursors in young women (modified intention-to-treat population)*
Outcomes at 15–60 monthsNumber of trials (n)Weighted event ratesRRR (95% CI)NNT (CI)
VaccineControl
Grade 2 CIN or worse5 (36 266)0.8%1.5%48% (37 to 57)138 (116 to 179)
Any grade CIN5 (24 613)0.7%1.9%64% (55 to 71)81 (73 to 95)
Persistent HPV infection at 6 months3 (14 207)0.9%4.0%77% (72 to 81)33 (31 to 35)
Persistent HPV infection at 12 months2 (7774)0.4%1.6%74% (59 to 84)86 (76 to 108)
External genital lesions2 (5981)1.1%3.5%69% (56 to 77)41 (37 to 51)
Serious adverse events6 (39 609)2.2%2.2%0% (−14 to 13)Not significant
  • *CIN  =  cervical intraepithelial neoplasia; other abbreviations defined in glossary. Weighted event rates, RRR, NNT, and CI calculated from data in article.