There are two vaccines available to protect women against developing CERVICAL CANCER. They protect against infection with certain strains of human papillomavirus (HPV). Both vaccines (Cervarix® and Gardasil®) protect against HPV types 16 and 18, generally contracted during sexual intercourse and which are responsible for causing around 70–75 per cent of cervical cancer. These HPV types also cause vulval and vaginal cancers in women, and anal cancers as well as some head and neck cancers in both men and women. One of the vaccines (Gardasil) also protects against genital WARTS caused by HPV types 6 and 11. Both vaccines consist of virus-like particles (VLPs), manufactured using the virus coat protein. VLPs have the outward appearance of the actual virus and provoke the vaccinated person into generating a powerful immune response. However, they contain no viral DNA so cannot themselves cause disease. They are administered as three injections over a six-month period. In the UK, the vaccination programme started in September 2008 and included girls aged 12–13 and 17–18. From September 2009, a further catch-up programme commenced for girls up to the age of 18. The Department of Health (DoH) in England & Wales has decided that the HPV vaccine to be used for the programme will be Cervarix.

For optimal protection, the vaccines should be administered before the onset of sexual activity, as they cannot eradicate an HPV infection which is already present. Currently follow-up data are available only up to six-and-a-half years, but statistical modelling suggests that immunity may persist for 30.

Both Gardasil and Cervarix show high efficacy, approaching 100 per cent, against HPV 16- and 18-related high-grade cervical intraepithelial neoplasia (CIN), and Gardasil has shown similar efficacy against genital warts. The VLPs in the two vaccines have been manufactured using different systems, and the adjuvants (non-immunogenic material which enhances the vaccines’ activity) used are also different. Although superficially similar, the differences between the two vaccines may turn out to be clinically relevant.

Both vaccines have shown early evidence of cross-protection against related HPV types. At present, this effect appears to be greater for Cervarix than Gardasil. Cross-protection may significantly raise the overall protection level.

Studies are also underway to evaluate the benefit of vaccinating older women (i.e. over 25 years old) and men, currently available in some other countries. It is important to realise that until the effect and longevity of HPV vaccination are proven, cervical screening must continue, although screening methods may need to be revised in time (see also CERVICAL SMEAR; IMMUNISATION).