Vaccines for the Prevention of Cervical Cancer

Two preventative vaccines have recently been developed to reduce the incidence of HPV-related disease including cervical cancer. These HPV "virus-like particle" vaccines contain no DNA and are not live/attenuated viruses. One of these vaccines, Gardasil (Merck) protects against HPV types 6, 11, 16, and 18 (quadravalent vaccine) and the other vaccine, Cervarix (GlaxoSmithKline), protects against types 16 and 18 (bivalent vaccine). At this time, only Gardasil has received FDA approval and licensing (granted in June 2006).

Gardasil can be administered to females ages 9 to 26. The intention is for the vaccine to be given prior to contact with HPV types 6, 11, 16, and 18 to prevent the development of disease. Therefore, it is recommended to be given to girls before they become sexually active.

Females who are already infected with HPV may still benefit from the vaccine, as they have most likely not been infected with all 4 types of the virus covered by the vaccine.

Gardasil is administered as 3 injections over 6 months. There seem to be only mild side effects which include: pain, swelling, itching, and redness at the injection site; fever; nausea; and dizziness. Gardasil cannot be administered to women who are pregnant.

In clinical trials, Gardasil was 100% effective against HPV strains 16 and 18, which are responsible for 70% of cases of cervical cancer. Gardasil was also 99% effective against HPV strains 6 and 11, which are responsible for 90% of cases of genital warts.

The cost for the three injection series is over $300. Individual costs will depend upon availability of insurance coverage and government programs.

One study found that vaccination of the entire population of 12 year old girls would prevent more than 200,000 HPV infections; 100,000 abnormal Pap tests; and 3,300 cases of cervical cancer.

Limitations of the current HPV vaccinations (and areas for further research) include:

• The vaccines do not protect against all cancer causing HPV types
• The vaccines do not treat existing HPV infections;
• The duration of protection and required length of protection to prevent cancer are unknown;
• The cost may be prohibitive in certain populations such as the medically underserved and uninsured;
• The need for a three-dose regimen may not be achievable in a population with poor follow up (such as the underserved or uninsured, or in migrant populations).

It is important that women continue cervical cancer screening even if they have received the HPV vaccine.