Reduction in HPV 16/18 prevalence in sexually active young women following the introduction of HPV immunisation in England

Abstract

Background: Reduction in the prevalence of vaccine type HPV infection in young women is an early indication of the impact of the HPV immunisation programme and a necessary outcome if the subsequent impact on cervical cancer is to be realised.

Methods: Residual vulva-vaginal swab (VVS) specimens from young women aged 16-24 years undergoing chlamydia screening in community sexual health services (formerly known as family planning clinics), general practice (GP), and youth clinics in 2010-2012 were submitted from 10 laboratories in seven regions around England. These specimens were linked to demographic and sexual behaviour data reported with the chlamydia test, anonymised, and tested for type-specific HPV DNA using a multiplex PCR and Luminex-based genotyping test. Estimated immunisation coverage was calculated and findings were compared to a baseline survey conducted prior to the introduction of HPV immunisation in 2008.

Results: A total of 4664 eligible specimens were collected and 4178 had a valid test result. The post-immunisation prevalence of HPV 16/18 infection was lowest in this youngest age group (16-18 years) and increased with age. This increase with age was a reversal of the pattern seen prior to immunisation and was inversely associated with estimates of age-specific immunisation coverage (65% for 16-18 year olds). The prevalence of HPV 16/18 infection in the post-immunisation survey was 6.5% amongst 16-18 year olds, compared to 19.1% in the similar survey conducted prior to the introduction of HPV immunisation.

Conclusions: These findings are the first indication that the national HPV immunisation programme is successfully preventing HPV 16/18 infection in sexually active young women in England. The reductions seen suggest, for the estimated coverage, high vaccine effectiveness and some herd-protection benefits. Continued surveillance is needed to determine the effects of immunisation on non-vaccine HPV types.

Keywords: CI; Cervarix; Confidence Interval; GP; General Practice; HC2; HPV; HPV immunisation; HPV prevalence; HR; High-risk; Human Papillomavirus; Hybrid Capture 2; LA; LR; LSOA; Linear Array; Low-risk; Lower Super Output Area; NCSP; National Chlamydia Screening Programme; OR; Odds ratio; PCR; PCT; PDH; PHE; Polymerase Chain Reaction; Primary Care Trust; Public Health England; Pyruvate dehydrogenase; REC; Research Ethics Committee; Surveillance; VVS; Vulva-vaginal Swab.

Fig. 1

Flow chart of specimen collection and testing and immunisation categories. * Inadequate result: the sample is HPV and housekeeping gene (PDH) negative; Insufficient result: not sufficient sample to be tested; Invalid result: other technical reason.

Fig. 2

Prevalence of vaccine HPV types (16/18) by age-group and survey period. * Vaccine coverage estimated using published data on national HPV coverage for each birth-cohort by year. In the 19–21 year old age-group this is calculated separately for those women who would have been offered the vaccine as part of the national HPV immunisation programme.

Fig. 3

Prevalence of non-vaccine high-risk HPV types by age-group and survey period. * Vaccine coverage estimated using published data on national HPV coverage for each birth-cohort by year. In the 19–21 year old age-group this is calculated separately for those women who would have been offered the vaccine as part of the national HPV immunisation programme.