Cervarix®—a vaccine that reduces the risk of cervical cancer by protecting against two high-risk types of human papillomavirus (HPV)—remains effective for more than six years. These results were published in the Lancet.
Human papillomaviruses consist of more than 100 different viruses. Some types of HPV cause warts on the hands or feet; others cause genital warts; and some have been linked with cancer, most notably cervical cancer. The types of HPV most commonly linked with cervical cancer are HPV16 and HPV18, but several other high-risk types contribute to cancer as well.
The types of HPV that cause cervical cancer or genital warts are transmitted sexually. HPV infection is extremely common and generally occurs soon after an individual becomes sexually active. Although most infections resolve on their own, some persist and can lead to precancerous or cancerous changes to the cervix, vulva, vagina, penis, and anus. HPV infection has also been linked to certain cancers of the head and neck.
Recognition of the link between HPV and cervical cancer led to the development of vaccines designed to prevent infection with certain high-risk types of HPV. Gardasil® protects against HPV types 6 and 11 (which are linked with genital warts) as well as the cancer-associated types 16 and 18. Cervarix protects HPV types 16 and 18 only.
In order to have the greatest impact, these vaccines will need to provide sustained protection against HPV infection. To evaluate the efficacy of Cervarix up to 6.4 years after vaccination, researchers evaluated information from studies conducted in girls and women between the ages of 15 and 25 years.
- Vaccine efficacy against infection with HPV16 or 18 was 95.3%.
- Vaccine efficacy against precancerous or cancerous changes to the cervix (cervical intraepithelial neoplasia 2+) linked with HPV16 or 18 was 100%.
- Vaccine efficacy against all precancerous or cancerous changes to the cervix (regardless of HPV type) was 71.9%.
These results indicate that Cervarix protects against HPV16/18 infections and precancerous or cancerous changes to the cervix for more than six years.
Reference: The GlaxoSmithKline Vaccine HPV-007 Study Group. Sustained efficacy and immunogenicity of the human papillomavirus (HPV)-16/18 AS04-adjuvanted vaccine: analysis of a randomised placebo-controlled trial up to 6.4 years. Lancet. 2009;274:1975-85.