Efficacy of Vaccination against HPV Infections to Prevent Cervical Cancer in France: Present Assessment and Pathways to Improve Vaccination Policies

Abstract

BackgroundSeventy percent of sexually active individuals will be infected with Human Papillomavirus (HPV) during their lifetime. These infections are incriminated for almost all cervical cancers. In France, 3,068 new cases of cervical cancer and 1,067 deaths from cervical cancer occurred in 2005. Two vaccines against HPV infections are currently available and vaccination policies aim to decrease the incidence of HPV infections and of cervical cancers. In France, vaccine coverage has been reported to be low.MethodsWe developed a dynamic model for the heterosexual transmission of Human Papillomavirus types 16 and 18, which are covered by available vaccines. A deterministic model was used with stratification on gender, age and sexual behavior. Immunity obtained from vaccination was taken into account. The model was calibrated using French data of cervical cancer incidence.ResultsIn view of current vaccine coverage and screening, we expected a 32% and 83% reduction in the incidence of cervical cancers due to HPV 16/18, after 20 years and 50 years of vaccine introduction respectively. Vaccine coverage and screening rates were assumed to be constant. However, increasing vaccine coverage in women or vaccinating girls before 14 showed a better impact on cervical cancer incidence. On the other hand, performing vaccination in men improves the effect on cervical cancer incidence only moderately, compared to strategies in females only.ConclusionWhile current vaccination policies may significantly decrease cervical cancer incidence, other supplementary strategies in females could be considered in order to improve vaccination efficacy.

Impact of human papillomavirus vaccination on anal cancer incidence in French women

“…We did not assume that individuals who cleared HPV infection developed natural immunity against HPV. This approach of natural history for HPV infections has been used in other HPV models (Myers et al, 2000;Goldie et al, 2003;Kulasingam and Myers, 2003;Sanders and Taira, 2003;Goldie et al, 2004;Taira et al, 2004;Ribassin-Majed et al, 2012), whereas some other published models assumed natural immunity against HPV using Susceptible-Infected-Removed (S-I-R) structure (Elbasha et al, 2010). Existence and length of natural immunity after HPV clearance is uncertain and not biologically proved.…”

“…The heterosexually mixing population was divided into 14 age groups ([14 to 19] (Hethcote, 1997;Elbasha et al, 2007) which simulated the distribution of the French population. Details on the demographic model are described in Ribassin-Majed et al (2012). Annual transition rates into age groups were defined by the demographic model.…”

“…Thus, we studied the impact of vaccination on HPV prevalence and anal cancer incidence using low (60 and 40%) vaccine efficacies. Another sensitivity analysis corresponding to a variation in the sexual mixing parameter is described elsewhere (Ribassin-Majed et al, 2012).…”

“…Markov model do not take into account herd immunity effect. Another paper assessed the impact of HPV vaccination on cervical cancers in French women using a dynamic model (Ribassin-Majed et al, 2012). To estimate the cost-effectiveness of vaccination policies, other cancers due to HPV may be considered.…”

A Novel Method to Value Real Options in Health Care: The Case of a Multicohort Human Papillomavirus Vaccination Strategy

“…35 Increasing vaccination coverage in girls aged o14 years may be expected to reduce the incidence of cervical cancer. 36 Lastly, a vaccination program that includes both boys and girls can be considered to be a 2-cohort strategy. In light of the results of the real option evaluation, involvement of both girls and boys aged 12 years in a national HPV program should be reconsidered.…”