A national HPV immunisation programme was initiated in Scotland in 2008 for 12-13 year olds with a 3 year “catch up” for those under the age of 18. In tandem with the national immunisation programme, a programme of longitudinal HPV surveillance was also initiated. Key elements of surveillance were yearly sampling and HPV genotyping of women attending for their first smear and the monitoring of both low and high grade lesion prevalence through interrogation of national databases. As age at screening debut is currently 20 in Scotland, we are able to robustly determine the impact of a national immunisation programme on rates of HPV infection and HPV associated disease.
Liquid-based cytology (LBC) samples from women attending their first cervical smear were genotyped for HPV and data linkage enabled HPV prevalence to be stratified by immunisation status. In addition, we analysed data from the National Colposcopy Clinical Information and Audit System (NCCIAS), a national colposcopy database which contains data on referral cytology, interventions and histology results associated with any colposcopy visit.
By linking vaccination, cervical screening, and HPV testing data, over the study period we found a decline in HPV types 16 and 18, significant decreases in HPV types 31, 33, and 45 (suggesting cross-protection), and a non-significant increase in HPV 51. In addition, among non-vaccinated women, HPV types 16 and 18 were significantly lower in 2013 than in 2009. We also observed significant reductions in all grades of cervical intraepithelial neoplasia associated (55% reduction of CIN 3, 50% reduction of CIN 2 and a 29% reduction of CIN 1) with 3 doses of the HPV vaccine.
This is one of the first studies to show demonstrable impact of the bivalent vaccine on HPV genoprevalence and associated disease at the population level. These data are very encouraging for countries that have national programmes which have achieved high vaccine uptake, as it suggests that herd protection in the unimmunised may also be realisable.
Cameron RL, Kavanagh K, Pan J et al. (2016) Human papillomavirus prevalence and herd immunity after introduction of vaccination program, Scotland, 2009–2013.
Emerg Infect Dis 22: 56–64.
Pollock KG, Kavanagh K, Potts A, Love J, Cuschieri K, Cubie H, Robertson C, Cruickshank M, Palmer TJ, Nicoll S, Donaghy M (2014) Reduction of low- and high-grade cervical abnormalities associated with high uptake of the HPV bivalent vaccine in Scotland.
Br J Cancer 111: 1824–1830.