A vaccine to prevent infections of four strains of human papilloma virus is available to girls ages 9 to 26. The 2006 approval of the vaccine was heralded because some strains of HPV can cause cervical cancer. Studies have continued, however, on whether the vaccine may be useful for other groups of people, such as boys and older women. A study published today in the Lancet suggests that women ages 25 to 45 not already infected with HPV may be protected by the vaccine as well.
Most people are exposed to HPV within five to 10 years of the first sexual experience. Thus, the vaccine was approved for girls in order to prevent infections that might occur between the ages of 15 to 25. The study, by researchers at the National Institute of Cancer in Bogota, Colombia, and an international group of collaborators, examined the vaccine's effectiveness in almost 4,000 women with no history of genital warts or cervical disease. The women received either the HPV vaccine or a placebo. After two years, researchers found four cases of infection or disease occurred in the vaccine group (91% effectiveness) compared with 41 in the placebo group. However, the researchers also found that, among women who were not completely vaccinated (the vaccine is a three-shot regimen) or who had pre-existing HPV infection, the vaccine was only 31% effective against all four strains of HPV.
Data on how the women faired after four years will become available later this year, according to Merck, the manufacturer of Gardasil. Based on that data, the company is expected to ask the Food and Drug Administration to approve the vaccine for women ages 25 to 45, thus opening the door to insurance reimbursement. The vaccine costs about $500.
An HPV vaccine made by GlaxoSmithKline, Cervarix, is under review by the FDA. Cervarix has also been show in studies to protect women up to the age of 55.
The HPV vaccine may become available to boys, too. A study presented in November at a medical meeting in Europe found that Gardasil helped prevent genital warts in boys and men. Genital warts can lead to anal and penile cancer in men. Merck has requested approval of the vaccine for boys ages 9 to 26.
-- Shari Roan
Photo credit: Charles Rex Arbogast / AP