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

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.

Human papillomavirus types in cervical dysplasia among young HPV‐vaccinated women: Population‐based nested case–control study

“…Compared both to previous reports of population‐based, type‐specific HPV prevalences in the same country and global meta‐analyses where HPV16 and 18 are the dominant causes of high‐grade CIN, it is remarkable that we find that the major oncogenic vaccine‐targeted HPV types 16 and 18 are now almost nonexistent among young vaccinated women in Sweden—even among those women who develop CIN. A recent evaluation of effectiveness of another HPV vaccine, Cervarix, demonstrated a strong reduction in prevalence of cervical disease (CIN1–3) and an obvious herd protection of those women who were not immunized . The contrast between increasing prevalence of low‐grade cytological abnormalities and declining low‐grade histological abnormalities (CIN1) implies low progressive potential of detected lesions, which is in line with our findings.…”

“…Strategies for surveillance/monitoring of HPV vaccination programs have commonly involved following the statistics of CIN lesions detected by screening in highly vaccinated cohorts. 19,27,30 Our data imply that this is insufficient as mere registry data on the occurrence of CIN lesions will not capture if their progressive potential has changed. Our data finding that HPV 16/18 has almost disappeared as a cause of CIN among young vaccinated women in Sweden suggests that the CIN lesions that are still diagnosed in this cohort have lower progressive potential.…”

“…Strategies for surveillance/monitoring of HPV vaccination programs have commonly involved following the statistics of CIN lesions detected by screening in highly vaccinated cohorts . Our data imply that this is insufficient as mere registry data on the occurrence of CIN lesions will not capture if their progressive potential has changed.…”

The remarkable impact of bivalent HPV vaccine in Scotland

“…In a linked paper, Palmer and colleagues (doi:10.1136/bmj.l1161) report findings from Scotland, where the combination of high coverage with bivalent HPV vaccine, young age of screening initiation, and high quality individual level data across the population, unequivocally show high vaccine effectiveness in young women against high grade cervical disease regardless of causal HPV type 4…”

“…All countries must now consider how they can best implement and evaluate vaccination, screening, and treatment programmes that support the World Health Organization’s call for elimination of cervical cancer as a public health problem 7. Scotland has shown that integrated registry systems are highly effective tools in achieving and evaluating high vaccine uptake,8 and in assessing subsequent outcomes,4 including screening performance 9…”