The American College of Obstetricians and Gynecologists recommended that girls get the required series of three doses (given over a six-month period) at age 9 or older; the American Academy of Pediatrics and the Centers for Disease Control and Prevention recommended the same, with a starting age of 11 or later. (Because HPV is normally spread by intimate contact, the vaccine is considered most effective when given before the beginning of sexual activity. It will not eradicate HPV if someone is already infected.)
Since 2006, about 8 million females in the U.S. have received at least one shot of Gardasil, according to the vaccine's maker, Merck & Co. of Whitehouse Station, N.J., which based these estimates on data from government and private insurers. Of the 100 known strains of HPV, about 30 cause cancer or genital warts. Two -- HPV-16 and HPV-18 -- are responsible for 70% of cervical cancers. Pre-market studies showed that the vaccine is 90% to 100% effective in thwarting the transmission of these two strains and two others, which are linked to 90% of genital warts.
The vaccine is expensive. It costs $360 for the series of three shots, and administrative fees can add $100 or more. Though insurance companies sometimes cover costs, the overall expense for vaccinating the nations' teenagers could run into billions, a bill that will affect taxpayers as the shots are given to recipients of government health programs and health insurance premiums rise.
The price may not be worth it, says Dr. Karen Smith-McCune, an obstetrician and gynecologist at the UC San Francisco School of Medicine. Because it takes years for cervical cancer to develop, it is easily preventable as long as HPV infection is detected early. Though the cancer is common in developing countries and kills more than 280,000 women worldwide every year, it is much less of a health threat in the U.S., she says, where 11,000 women are diagnosed with the disease annually, and about 3,700 will die of it.
The comparatively low U.S. incidence of cervical cancer is due to one of the public health system's triumphs: widespread use of Pap smears, which detect abnormal cervical cells so they can be removed before they turn into cancers. Adoption of the Pap test caused a reduction of cervical cancer rates by 74% between 1955 and 1992, according to the American Cancer Society. Rates continue to drop by 4% each year.
