Smith-McCune and other critics of Gardasil also note that up to 90% of HPV infections in adolescents clear up on their own -- meaning that cervical cancer will not develop even in most women infected with the most aggressive type of HPV. In other words, a woman's risk of developing cervical cancer is already extremely low, and the immune system normally makes short work of HPV without outside help.
Even if women get the vaccine, they still need to continue annual Pap screenings because they could contract other cancer-causing HPV strains that the vaccine does not fight.
"The crux of it is that we know how to prevent cervical cancer," Smith-McCune says. "One of the key questions is whether this huge outlay of money for the vaccine is a better strategy than reaching out to the women who aren't getting Pap tests and follow-ups."
It is not yet proven that Gardasil actually prevents cervical cancer, which can take a decade to develop after HPV infection, because tests of the vaccine before the FDA greenlighted it didn't run long enough to prove that conclusively. "Even though it guards against two HPV strains, the other HPV types need to be taken into account," Smith-McCune says. "It will take a long time before we know the true efficacy of the vaccine."
Even doctors who helped devise the vaccine point out that Pap screening may be more effective in cutting cervical cancer rates. "If we vaccinate every single 12-year-old, it should reduce by half the number of cervical cancers in the next 35 years," says Dr. Diane Harper, director of the Gynecologic Cancer Prevention Research Group at Dartmouth Medical School in Hanover, N.H., and a lead researcher in the development of the HPV vaccine. "With Pap screening, we've reduced it by nearly 75%."
Then there is the issue of side effects. When the vaccine was tested in more than 11,000 females age 9 to 26 before its FDA approval, no serious ones emerged, though some subjects felt soreness at the injection site and, in rare instances, fainted after the shot.
But an analysis released June 30 by the Washington, D.C.-based public interest group Judicial Watch raised some red flags. Judicial Watch obtained records from the FDA's Vaccine Adverse Event Reporting System (VAERS), a voluntary system used by doctors, patients and drug companies to report side effects with vaccines to the federal agency. The report revealed that since the vaccine's 2006 approval, when girls began getting it, nearly 9,000 had bad health events after receiving Gardasil. The incidents included 10 miscarriages, 78 severe outbreaks of genital warts and six cases of Guillain-Barre syndrome, an autoimmune disorder that can result in paralysis. There were also 18 reported deaths.
Since the FDA's VAERS is known to catch perhaps 10% of adverse events at best, according to a 2004 report in the New England Journal of Medicine by the FDA, the actual numbers may be far higher.
It is difficult to prove whether the vaccine was the culprit behind these side effects -- just because two events happen, it does not mean that one caused the other, says Dr. Laurie E. Markowitz, an epidemiologist at the CDC who has had her own daughter vaccinated. The deaths, and all the other serious events, could have happened in the absence of the vaccine, she says.
Markowitz remains convinced the vaccine is safe. "The CDC and the FDA checked out these reports very carefully," she says. "And we've done calculations for the number of cases reported and the number of cases that you'd find in the general population, and we have not found an increase."
Given these caveats, should girls be getting the shots?
Most major medical groups still think Gardasil should be part of routine immunizations for 11- and 12-year-old girls.
Shots still strongly urged
There is more than the matter of cancer prevention, says Dr. Joseph A. Bocchini, chief of pediatric infectious disease at Louisiana State University Health Sciences Center in Shreveport and chairman of the American Academy of Pediatrics committee on infectious diseases. The vaccine could spare hundreds of thousands of women from the psychological trauma and physical pain of a cycle of follow-up tests when they have an abnormal Pap test result and the treatments for pre-cancerous lesions that can cause infertility.
"You can actually prevent these infections and the cervical abnormalities that require more invasive interventions," he says.
Whether the shots should be mandatory -- a step that has been considered by Texas, Michigan and Virginia -- is another issue. "This decision should be up to parents, and mandates are silly," says Harper of Dartmouth. "While the vaccine will improve the health of American women, its real benefit is in the developing world. And no matter what, Pap screening shouldn't be neglected. That's still our best safety net."