The effects of behavioural patterns on the potential success of the HPV vaccine.
by
Victoria Brown
University of Bath, UK
Coauthors: Dr. K. A. J. White (University of Bath)

In recent years, links between the human papillomavirus (HPV) and cervical cancer in women has led to the development of a vaccine to protect against HPV as a preventative measure for cervical cancer (Arbyn and Dillner 2007). A national vaccination pilot in the UK targets vaccination at pre-teenage girls, the majority of whom are not yet sexually active (JCVI HPV Sub-group minutes, September 2006); discussion of other target groups, such as the equivalent male cohort, is also taking place.

The vaccine is administered on three separate occasions and information from a clinician suggests that if one of these is missed, then the vaccine will not be an effective barrier to HPV. The cost of the triple dose is £240.

We are interested in exploring the impact of the vaccine in relation to behavioural traits demonstrated at the population level. In particular, given that the vaccine may only be effective for 5-10 years, how does the onset of sexual activity in the population affect the efficacy of the vaccine in eradicating the virus?

To address such questions, we develop a model system which describes the spread of the virus in a heterosexual population (males and females are explicitly modelled), where individuals may either be sexually active or not. We focus the analysis of the model on the interaction between three parameters: the proportion of the female population that is initially vaccinated, the rate at which females become sexually active and the proportion of vaccinated individuals that are still sexually inactive when the vaccine loses its efficacy. Model parameters are estimated using published datasets.

We discuss the results of our analysis; in particular, we describe the conditions under which HPV might be eradicated from a population with different behavioural patterns. We will discuss extensions to this work; in particular, the extension to consider an explicit age dependent model.

References:

Arbyn and Dillner 2007: Marc Arbyn and Joakim Dillner, Review of current knowledge on HPV vaccination: An Appendix to the European Guidelines for Quality Assurance in Cervical Cancer Screening, Journal of Clinical Virology, 38 (2007).

JCVI HPV Sub-group minutes: Department of Health, Joint Committee on Vaccination and Immunisation, Minutes of the HPV Sub-group meeting, Wednesday 22 September.

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Date received: April 16, 2008