Before the end of the decade, preteens going to the doctor for the usual booster shotstetanus, diphtheria, and perhaps an annual flu shotmay get a new jab. The vaccine would not only protect them against one of the most common sexually transmitted infections but also prevent cervical canceralmost eliminating that form of malignancy, in fact, and saving the lives of nearly a quarter million women worldwide each year. But even before studies of the vaccines effectiveness are complete, conservative Christian groups are expressing concerns about inoculating adolescents against sexually transmitted infections.
A study published in the November 13 issue of British medical journal The Lancet showed that women who received all three doses of the vaccine, made by GlaxoSmithKline, maintained a strong immune response against the virus that causes cervical cancer, and that this immunity lasts for at least two years. The vaccine is one of two being developed against cervical cancer; Merck makes the second. It’s fabulous, says Diane Harper, who directed the study and who heads research on prevention of gynecological cancer at Dartmouth Medical School. It’s safe, it’s easy to make, and it’s amazingly effective.
Both the Merck and GlaxoSmithKline vaccines target human papillomavirus, or HPV, the virus that causes cervical cancer. Spread through intimate skin-to-skin contact, HPV can also cause genital warts. There are more than 100 strains of HPVs, many of them harmless; the Glaxo vaccine is aimed specifically at the two strainsknown as HPV-16 and HPV-18that account for about 70 percent of cervical cancers. Among women who received at least one of three scheduled doses, the vaccine was 95 percent effective at protecting against persistent infection with HPV-16 and HPV-18 throughout the 27 months of the trial. Merck’s version, which adds protection against HPV-6 and HPV-11 (the viruses that cause genital warts) has shown similar results. Both companies are conducting final, large-scale tests of their vaccines, and Merck plans to submit its vaccine for approval by the U.S. Food and Drug Administration by the end of 2005.
The vaccines’ potential is undisputed. It’s really exciting, says Gillian Sanders, a medical decision analyst at Duke University who has evaluated HPV vaccination strategies. It’s very clear these viruses are causing cervical cancer, and there’s a vaccine that’s showing to be very effective. That could make a huge difference in developing countries. Globally, more than 500,000 women suffer cervical cancer each year. It is the third most common cancer in women worldwide and the leading cancer killer among women in developing countries. In the United States, widespread Pap screening has reduced deaths from cervical cancer dramatically, but the disease still strikes some 15,000 women each year and kills about 5,000. By targeting the forms of HPV associated with the majority of cervical cancer cases, the vaccines have the potential to save as many as 175,000 women annually.
The controversy begins with researchers’ efforts to determine the best vaccination program to protect the largest number of women. Several published studies have modeled possible programs; the consensus is that the most cost-effective strategy is to inoculate 12-year-old girls.
Researchers acknowledge the obvious: The question in everybody’s mind is, will parents vaccinate their adolescent children against what is essentially a sexually transmitted infection? says Evan Myers, chief of the division of clinical and epidemiological research at Duke University Medical Center ‘s department of obstetrics and gynecology. Myers co-authored a 2003 study of the potential health and economic benefits of an HPV vaccine program and has consulted for Merck’s HPV vaccine program. Most cases of HPV occur between ages 15 and 25, with a large increase beginning around age 19, Myers says; however, adolescents have proved difficult to reach with vaccines in the past. The hepatitis B vaccine, for instance, was originally recommended for adolescents but is now generally given as part of the infant series. Targeting 12-year-olds gives doctors the best chance to vaccinate the most children before they are at risk from HPVand eventual cervical cancer.