This work is part of the NIHR-funded MEMVIE project.

HPV is a sexually transmitted infection (STI) that can lead to cervical cancer in women, and genital warts in both sexes. There are multiple strains of the virus, with types 16 and 18 being strongly correlated with cervical intraepithelial neoplasmia (CIN) in women, and types 6 and 11 shown to cause genital warts.

There are currently two HPV vaccines available commercially, a bivalent vaccine (Cervarix) protecting against the cancer-causing strains, and a quadravalent vaccine (Gardasil) which additionally protects against the main warts-causing strains. The UK NHS originally vaccinated teenage girls (aged 12-13) with the bivalent vaccine, starting in 2008, although has recently switched to the quadravalent vaccine. A nonavalent vaccine (protecting against 9 HPV strains, including the four mentioned above) is currently in development.

The overwhelming majority of the work on HPV modelling has been completed. This work involved: the development of an individual-based model for the spread of HPV, parameter inference using a variety of data sources and forward simulation integrated with health-economics to produce the output required by JCVI concerning gender neutral vaccination.

Constructing an epidemiological model for the spread of HPV involved accurately capturing the dynamics of HPV transmission, necessitating the development of novel mathematical models simulating sexual partnerships between individuals. To aid with this we employed the three NATSAL (National Survey of Sexual Attitudes and Lifestyles) surveys undertaken in the UK in 1990, 2000 and 2010, which asked a subpopulation of the UK a variety of questions related to their history of sexual partnerships, along with attitudes towards a variety of sexual practices (for example, homosexuality, and polygamy within relationships). We used available empirical studies on pre-vaccination HPV levels to fit our model to, then used the fitted model to test a variety of vaccination strategies, including the current NHS policy (teenage girls). The cost-effectiveness of alternative vaccination strategies were examined using forward simulation integrated with health-economics, which accurately estimated costs to the NHS for each case of HPV and, where appropriate, cervical cancer caused by HPV, and compared this to the cost of distributing the HPV vaccine and its efficacy (currently estimated to protect individuals for 20 years).

Associated publications

1. Datta S, Pink J, Medley GF, Petrou S, Staniszewska S, Underwood M, Sonnenberg P & Keeling MJ. (2019) Assessing the costeffectiveness of vaccination strategies for adolescent girls and boys. BMC Infectious Diseases 19: 552. doi: 10.1186/s12879-019-4108-y.
2. Datta S, Mercer CH & Keeling MJ. (2018) Capturing sexual contact patterns in modelling the spread of sexually transmitted infections: Evidence using Natsal-3. PloS ONE 13(11): e0206501. doi: 10.1371/journal.pone.0206501
3. Leng T & Keeling MJ (2018) Concurrency of partnerships, consistency with data, and control of sexually transmitted infections.Epidemics 25: 35-46. doi: 10.1016/j.epidem.2018.05.003
4. Pink J, Parker B &Petrou S (2016) Cost effectiveness of HPV vaccination: a systematic review of modelling approaches. Pharmacoeconomics 34(9): 847-861. doi: 10.1007/s40273-016-0407-y

MEMVIE:

A 6-year project funded by NIHR to provide advice to JCVI.

Researchers involved:

Matt Keeling (Professor, joint between Warwick Mathematics Institute and School of Life Sciences)

Stavros Petrou (Professor in Health Economics, Warwick Medical School)

Graham Medley (Professor, London School of Hygiene and Tropical Medicine)

Sophie Staniszewska (Leader of Patient and Public Involvement, Warwick Medical School)

Martin Underwood (Director of Clinical Trials Unit, Warwick Medical School)

Ed Hill (Postdoctoral researcher, Warwick Mathematics Institute)