Success of HPV vaccination is now a matter of coverage
Source: The Lancet Oncology, Volume 13, Issue 1, Pages 10-12, January 2012 In a pair of articles in The Lancet Oncology, Lehtinen and colleagues and Wheeler and colleagues present 4-year end of study data from a trial of a prophylactic human papillomavirus (HPV)-16/-18 vaccine (Cervarix, GlaxoSmithKline) in young women aged 15-25 years. From a public-health perspective, these studies have several important contributions. The results assure us that among HPV-naive women in the 15—25 year age range, Cervarix has extremely high efficacy against HPV-16/-18-associated persistent infection, CIN2, and CIN3 or worse, the best ethical surrogate endpoint for prospective studies of invasive cervical cancer risk. Combined with other trials of Cervarix and Merck's quadrivalent Gardasil vaccine against HPV-16/-18/-6/-11,3 the evidence is strong for near 100% prophylactic vaccine efficacy in HPV-naive women at any age. Nonetheless, even with vaccine efficacy near 100% in HPV-naive women, the efficacy in the total vaccinated cohort decreased steeply with increasing age, showing an absence of therapeutic effect against already-acquired infections and associated lesions. We know from natural history studies that new HPV transmission (incidence, not prevalence) decreases with age in most cultures.4 Together, natural history data and results of trials for both vaccines suggest that vaccination before sexual debut, or around the time of menarche, will achieve the greatest reduction in cervical cancer rates. The 4-year trial data shows no decline in vaccine efficacy in HPV-naive women with time since vaccination.1 We know from other trials of the two vaccines that the duration of protection is several [...]