title: Quadrivalent HPV vaccine effectiveness against high-grade cervical lesions by age at vaccination: A population-based study.
abstract: Human papillomavirus (HPV) types 16/18, included in HPV vaccines, contribute to the majority of cervical cancer, and a substantial proportion of cervical intraepithelial neoplasia (CIN) grades 2/3 or worse (CIN2+/CIN3+) including adenocarcinoma in situ or worse. The aim of this study was to quantify the effect of quadrivalent HPV (qHPV) vaccination on incidence of CIN2+ and CIN3+. A nationwide cohort of girls and young women resident in Sweden 2006-2013 and aged 13-29 (n = 1,333,691) was followed for vaccination and histologically confirmed high-grade cervical lesions. Data were collected using the Swedish nationwide healthcare registers. Poisson regression was used to calculate incidence rate ratios (IRRs) and vaccine effectiveness [(1-IRR)x100%] comparing fully vaccinated with unvaccinated individuals. IRRs were adjusted for attained age and parental education, and stratified on vaccination initiation age. Effectiveness against CIN2+ was 64% (IRR = 0.36, 95%CI = 0.27–0.47) for those initiating vaccination before age 17, and 25% (IRR = 0.75, 95%CI = 0.66–0.86) and 14% (IRR = 0.86, 95%CI = 0.73–1.01) for those initiating vaccination at ages 17–19, and at ages 20–29, respectively. Vaccine effectiveness against CIN3+ was similar to vaccine effectiveness against CIN2+. Results were robust for both women participating to the organized screening program and for women at prescreening ages. We show high effectiveness of qHPV vaccination on CIN2+ and CIN3+ lesions, with greater effectiveness observed in girls younger at vaccination initiation. Continued monitoring of impact of HPV vaccination in the population is needed in order to evaluate both long-term vaccine effectiveness and to evaluate whether the vaccination program achieves anticipated effects in prevention of invasive cervical cancer.
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Eva
authors: E
authors: Herweijer
authors: Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.
authors: Karin
authors: K
authors: Sundström
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Alexander
authors: A
authors: Ploner
authors: Department of Monitoring and Evaluation, Public Health Agency of Sweden, Sweden.
authors: Ingrid
authors: I
authors: Uhnoo
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Pär
authors: P
authors: Sparén
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Lisen
authors: L
authors: Arnheim-Dahlström
mesh_terms: D000328:Adult; D017677:Age Distribution; D015331:Cohort Studies; D005260:Female; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18 / Q000276:immunology*; D006801:Humans; D030361:Papillomavirus Infections / Q000276:immunology / Q000517:prevention & control*; D002583:Uterine Cervical Neoplasms / Q000517:prevention & control* / Q000821:virology; D014611:Vaccination; D064166:Vaccine Potency; D055815:Young Adult
chemical_list: D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18
keywords: HPV vaccination; high-grade cervical lesions; nationwide; vaccine effectiveness