Projected impact of Cervarix™ vaccination on oncogenic human papillomavirus infection and cervical cancer in the United Kingdom.

We developed a dynamic compartmental model to assess the impact of HPV Universal Mass Vaccination (UMV) with Cervarix™, which offers protection against HPV16/18 and cross-protection against other cancer-causing types, using up-to-date efficacy data. Analyses were performed in the UK because of the large amount of high quality epidemiological data available. For each HPV type/group of types considered, the model was calibrated to 14 epidemiological datasets (prevalence of HPV infection, cervical intraepithelial neoplasia (CIN): CIN1, CIN2, CIN3 pre-screening and cervical cancer (CC) incidence over 10 y post-screening). Impacts of cross-protection, female catch-up vaccination, and additional male vaccination on oncogenic infections, high-grade CIN (CIN2+) and CC were evaluated. Our results show that female UMV with 80% coverage and cross-protection against high-risk types resulted in 81% CIN2+ and 88% CC reductions vs. 57% and 75%, respectively, without cross-protection. Vaccinating 40% of males and 80% of females was equivalent to 90% female-only coverage regarding CIN2+ (87% and 87%, respectively) and CC (93% and 94%, respectively) reductions. Female-only coverage of 80% substantially reduced male HPV16 and 18 infection due to herd protection (74% and 89%, respectively). Increasing female coverage to 90% reduced HPV16 and HPV18 infections in males relatively similarly to 80% female combined with 40% male coverage. Model outcomes strengthen previous conclusions about the significant added value of Cervarix™ cross-protection for CC prevention, the primary HPV vaccination public health priority. Regarding female CC prevention and male HPV16/18 infection, small increases in female coverage induce similar benefits to those achieved by additionally vaccinating men with 40% coverage.

A mathematical model of hepatitis a transmission in the United States indicates value of universal childhood immunization.

BACKGROUND: US recommendations issued in 1999 for hepatitis A (HA) childhood immunization varied according to regional HA incidences prior to vaccination. Mathematical models of HA transmission, especially those accounting for herd protection, can be useful in formulating new, highly effective recommendations that could lead to disease elimination. METHODS: A mathematical model of HA transmission was designed to assess the impact of different vaccination strategies on the evolution of HA infection over time in the United States. The model represents HA transmission dynamics and is stratified by age and regions defined in the Advisory Committee for Immunization Practices 1999 recommendations. The model accounts for herd protection and HA importation, using an age-dependent "force of infection" varying over time as a function of the prevalence of subjects with infectious HA. RESULTS: The model predicts a clear benefit of vaccinating all US children at as young an age as possible. Nationwide routine immunization at 1 year of age with 70% coverage would prevent 57% of additional cases during the period 1995-2029, compared with the continuation of the regional strategy of vaccinating children at 2 years of age, as recommended by the Advisory Committee for Immunization Practices in 1999. In contrast, the model also predicts that nationwide routine immunization for children 12 years of age only would result in a 14% increase of HA cases during the period 1995-2029, compared with the number of cases predicted with the regional strategy of the immunization of 2-year-olds. CONCLUSIONS: These findings highlight the importance of accounting for herd protection induced by early childhood HA vaccination. They also support the very recent Advisory Committee for Immunization Practices recommendations for universal HA immunization of 1-year-olds.