Response

Extract

We thank Suba et al. for highlighting important issues about the durability of protection afforded by human papillomavirus (HPV) vaccination and the potential implications of vaccination for cervical cancer screening.

Approximately a decade after the availability of HPV prophylactic vaccines, reports of vaccinated women developing “breakthrough” cervical cancer precursors remain anecdotal, suggesting that the immune response is durable, and therefore the efficacy of vaccination will likely be longstanding ( 1 ). This view is bolstered by biological evidence, including the observation that vaccine antibody titers are several-fold higher than those induced by natural infection ( 2 ), mathematical modeling of the kinetics of antibody decay that suggests that the immune response may persist for 30 years ( 3 ), and a substantial recall response to antigen challenge several years after vaccination that suggests robust immunological memory ( 4 ). Furthermore, the ecological data from Australia reported by Brotherton et al. ( 5 ) (and cited by Suba et al.) show early reductions in the overall incidence of high-grade precursors among the youngest women after a population-wide HPV vaccination program, providing further credence for optimism. However, continued surveillance is needed and would be enhanced by infrastructure linking vaccination and screening registries ( 5 ). Brotherton et al. also note that 96% of women aged 18 to 28 years surveyed knew that continued cervical screening was required in the postvaccination era ( 5 ), suggesting that introduction of HPV vaccines will not adversely affect screening behaviors.