Peer-reviewed article

Prevalence of cervical disease at age 20 after immunisation with bivalent HPV vaccine at age 12-13 in Scotland: retrospective population study

Timothy J. Palmer, Lynn Wallace, Kevin G.J. Pollock, Kate S. Cuschieri, Chris Robertson et al. · 3 Apr 2019

Summary

Written by AI, not yet AICS's view · claude-haiku-4-5-20251001

This study examined cervical disease rates in 20-year-old women in Scotland who received the bivalent HPV vaccine at age 12-13 compared to unvaccinated women. Vaccinated women showed an 89% reduction in the most serious type of cervical disease (CIN grade 3 or worse) and an 88% reduction in moderate disease (CIN grade 2 or worse). The vaccine was more effective when given at younger ages, and there was evidence of protection even in unvaccinated girls through herd immunity effects. The findings indicate the bivalent HPV vaccine is highly effective at preventing preinvasive cervical disease.

Key points

89% reduction in cervical intraepithelial neoplasia (CIN) grade 3 or worse in vaccinated women (from 0.59% to 0.06%)
88% reduction in CIN grade 2 or worse (from 1.44% to 0.17%)
79% reduction in CIN grade 1 (from 0.69% to 0.15%)
Vaccine effectiveness was 86% for CIN grade 3 or worse when given at age 12-13, dropping to 51% when given at age 17
Evidence of herd protection against high grade cervical disease found in unvaccinated girls in vaccinated cohorts

Limitations

This is a retrospective study using existing screening records from one country; it cannot determine long-term outcomes beyond age 20, and the findings are specific to the bivalent HPV vaccine formulation used in Scotland during this period.

Abstract

OBJECTIVE: To quantify the effect on cervical disease at age 20 years of immunisation with bivalent human papillomavirus (HPV) vaccine at age 12-13 years. DESIGN: Retrospective population study, 1988-96. SETTING: National vaccination and cervical screening programmes in Scotland. PARTICIPANTS: 138 692 women born between 1 January 1988 and 5 June 1996 and who had a smear test result recorded at age 20. MAIN OUTCOME MEASURES: Effect of vaccination on cytology results and associated histological diagnoses from first year of screening (while aged 20), calculated using logistic regression. RESULTS: 138 692 records were retrieved. Compared with unvaccinated women born in 1988, vaccinated women born in 1995 and 1996 showed an 89% reduction (95% confidence interval 81% to 94%) in prevalent cervical intraepithelial neoplasia (CIN) grade 3 or worse (from 0.59% (0.48% to 0.71%) to 0.06% (0.04% to 0.11%)), an 88% reduction (83% to 92%) in CIN grade 2 or worse (from 1.44% (1.28% to 1.63%) to 0.17% (0.12% to 0.24%)), and a 79% reduction (69% to 86%) in CIN grade 1 (from 0.69% (0.58% to 0.63%) to 0.15% (0.10% to 0.21%)). Younger age at immunisation was associated with increasing vaccine effectiveness: 86% (75% to 92%) for CIN grade 3 or worse for women vaccinated at age 12-13 compared with 51% (28% to 66%) for women vaccinated at age 17. Evidence of herd protection against high grade cervical disease was found in unvaccinated girls in the 1995 and 1996 cohorts. CONCLUSIONS: Routine vaccination of girls aged 12-13 years with the bivalent HPV vaccine in Scotland has led to a dramatic reduction in preinvasive cervical disease. Evidence of clinically relevant herd protection is apparent in unvaccinated women. These data are consistent with the reduced prevalence of high risk HPV in Scotland. The bivalent vaccine is confirmed as being highly effective vaccine and should greatly reduce the incidence of cervical cancer. The findings will need to be considered by cervical cancer prevention programmes worldwide.