Investigating the impact of Britain's HPV vaccination program to inform national public health interventions in the next decade

Most cervical cancer cases are caused by infection with high-risk human papillomavirus (HPV), particularly HPV types 16 and 18. Annually, there are approximately 3,200 new cases of cervical cancer in the UK. However, HPV-related cancers, such as cervical cancer, can be prevented through vaccination. Cervical cancer can also be prevented through early detection and treatment of abnormal cells through routine cervical cancer screening (offered to all women aged 25 and over). In the UK, the HPV vaccine (bivalent Cervarix until September 2012, quadrivalent Gardasil from 2012-2021, and 9-valent Gardasil 9 in 2021/2022) has been offered to all girls aged 12 or 13 years since 2008. The program was expanded to include boys in the same age bracket in July 2018, as well as men who have sex with men (MSM) in April 2018. Early evidence, both in the UK and globally, suggests that the vaccination program has been highly successful at reducing HPV prevalence among vaccinated individuals and therefore preventing HPV-related cancers, though it is unclear whether the effects and uptake are consistent across population groups. It is also unclear whether 'type replacement' of the vaccine-preventable HPV types (e.g. high-risk HPV types 16/18) with non-vaccine types, or cross-protection of non-vaccine types, will occur. The decennial National Survey of Sexual Attitudes and Lifestyles (Natsal) study is a representative population survey on sexual health in Britain. Natsal-2 (1999-2001) provided baseline type-specific HPV prevalence used to inform the design of the vaccination program, and the most recent Natsal study (Natsal-3; 2010-12) captured the early effects of the initial catch-up HPV vaccination program and inequalities in cervical cancer screening uptake. Data from Natsal-4 (2022-23) will be crucial to determine the effect of these HPV interventions at a population level. This project will use data from the Natsal-4 study, as well as routine surveillance data, to analyse type-specific HPV prevalence and uptake of HPV vaccination and cervical cancer screening uniquely linked to a range of demographic and behavioural factors to assess impact on inequalities and opportunities for targeted interventions. Over the next ten years, these data will be critical to inform national public health policy and mathematical models estimating a range of interventions, including adaptations to vaccine schedule (e.g. to single dose), cervical cancer screening, and roll out to younger age groups.