Cross protection against HPV might prevent type replacement

Abstract

www.thelancet.com/infection Vol 13 March 2013 195 1 Heitmann ER, Harper DM. Prophylactic HPV vaccines and prevention of cervical intraepithelial neoplasia. Curr Obstet Gynecol Rep 2012; 1: 95–105. 2 Khan MJ, Castle PE, Lorincz AT, et al. The elevated 10-year risk of cervical precancer and cancer in women with human papillomavirus (HPV) type 16 or 18 and the possible utility of type-specifi c HPV testing in clinical practice. J Natl Cancer Inst 2005; 97: 1072–79. 3 Malagon T, Drolet M, Boily MC, et al. Cross-protective effi cacy of two human papillomavirus vaccines: a systematic review and meta-analysis. Lancet Infect Dis 2012; 12: 781–89. 4 Wheeler CM, Castellsague X, Garland SM, et al, for the HPV PATRICIA Study Group. Cross-protective effi cacy of HPV-16/18 AS04-adjuvanted vaccine against cervical infection and precancer caused by nonvaccine oncogenic HPV types: 4-year end-ofstudy analysis of the randomised, double-blind PATRICIA trial. Lancet Oncol 2012; 13: 100–10. 5 Kahn JA, Brown DR, Ding L, et al. Vaccine-type human papillomavirus and evidence of herd protection after vaccine introduction. Pediatrics 2012; 130: 249–56. or greater (CIN2+). Additionally, Wheeler and colleagues showed that Cervarix provided cross protection against persistent infection or CIN2+ caused by HPV 51, 52, and 56 in HPV-naive populations. Estimates of the duration of cross protection of Cervarix are restricted over 9·4 years by loss of participants assigned to placebo from follow-up of trial populations, which makes it seem as though the substantial original cross-protection effi cacy decreases. On the basis of the 9·4 year data, whether effi cacy truly decreases is unclear, but the continuing existence of 9·4 year effi cacy is important. Findings from a 2012 study showed a 13·6% increase in the incidence of non-vaccinerelated HPV types in adolescents and women (aged 13–26 years) given Gardasil within 3 years of vaccination (ie, the postsurveillance period) by comparison with adolescents given Gardasil in the presurveillance period when vaccination had just been approved before implementation. This type replacement has not been studied for progression to CIN 3+ disease, but raises concerns about future cervical cancers. Cross protection could become important for the restriction of type replacement CIN 3+ disease. Populations are exclusively vaccinated with either Cervarix or Gardasil, so whether Cervarix’s better cross protection suppresses the typeplacement suggested by studies of Gardasil-vaccinated populations should become apparent.