Prophylactic HPV vaccine programs primarily targeting adolescent populations prior to sexual debut constitute a major worldwide public-health initiative. We assessed the global real-world effect of the quadrivalent HPV (4vHPV) vaccine containing HPV types 6/11/16/18 over its first decade of use.
We systematically searched PubMed and Embase for peer-reviewed articles published in any language between January 2007 and November 2015 to capture observational studies (including national registries) evaluating the impact or effectiveness of 4vHPV vaccination against HPV infection, anogenital warts, low-grade cervical cytological and histological abnormalities (ASCUS, LSIL, CIN1), and/or high-grade cervical lesions (HSIL, ASC-H, CIN2, CIN3, adenocarcinoma in situ (AIS), cervical cancer). We limited the search to articles reporting on the 4vHPV vaccine.
A rapid and dramatic reduction in the prevalence of HPV 6/11/16/18 infection (~40% to 80%) and genital warts (up to 90%) after introduction of 4vHPV vaccination programs was demonstrated in young women in Australia, Europe, North America, and New Zealand. In subsequent years, as successive birth cohorts began cervical screening, reductions in cervical lesions started to become apparent (e.g., ~10% to 35% reduction in low-grade abnormalities, ~25% to 80% reduction in high-grade abnormalities). In Australia and Denmark where programs have achieved high and timely vaccination coverage and include catch-up vaccination, respective reductions as high as 47% and 80% in CIN3 lesions have been reported in the youngest cohorts vaccinated shortly after program implementation. Overall, while 4vHPV vaccine programs have been successful in reducing HPV 6/11/16/18 infection and HPV-related disease, the actual estimates of impact and effectiveness vary regionally based on age at vaccination, vaccination coverage, the number and timing of vaccine doses, length of follow-up, cervical cancer screening recommendations and practice, statistical power, completeness and accuracy of data sources, and analytic methods.
Over the last decade, the impact of HPV vaccines in real-world settings has become increasingly evident, especially where there is broad coverage of the target population. Despite high vaccine effectiveness, the full public-health potential of HPV vaccination is unfortunately far from being realized. Many preventable HPV-related diseases continue to present major public health challenges for both developing and developed nations, underscoring the need for wide-reaching HPV vaccination programs with high population coverage prior to sexual debut.