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Biomedicine

Vaccine Truth or Dare

A new vaccine in the works could prevent cervical cancer. But will it ever reach those who would benefit most?

Before the end of the decade, preteens going to the doctor for the usual booster shots—tetanus, diphtheria, and perhaps an annual flu shot—may get a new jab. The vaccine would not only protect them against one of the most common sexually transmitted infections but also prevent cervical cancer—almost 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 vaccine’s 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 strains—known as HPV-16 and HPV-18—that 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 HPV—and eventual cervical cancer.

Ideally, Myers says, the vaccine companies would like to see the vaccine added to the recommended pediatric immunization schedule. According to Eliav Barr, who heads Merck’s clinical research program on the HPV vaccine, both the U.S. Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices and the American Academy of Pediatrics have expressed intense interest in the HPV vaccines. Barr also believes that making the inoculation part of the series required for school entry could be the most effective way to ensure widespread vaccination. These requirements are set by each state individually, usually in accordance with guidelines established by the Advisory Committee on Immunization Practices. “The key thing with vaccinations is reaching the hard to reach,” he says. “Middle-school entry and high-school entry requirements have been extremely effective at boosting coverage [for other vaccines] to levels really consistent with the best benefits available.”

Opponents of such a requirement note that it wouldn’t hurt Merck’s or Glaxo’s bottom line. “This thing is motivated by money as usual—and in a worldview that not everyone subscribes to,” says Leslee Unruh, founder of the Abstinence Clearinghouse. Unruh believes that abstinence-only sexual education offers a better approach to preventing the spread of all sexually transmitted diseases. Other Christian values groups, such as Concerned Women for America and the Family Research Council, echo her point of view.

“We know that there is what could easily be called an epidemic of HPV infection, and that needs to be taken seriously,” says Pia de Solenni, an ethicist who serves as director of life and women’s issues at the Family Research Council. “However, our concern would be that [a vaccine] really isn’t comprehensive, especially when you’re talking about administering it to 12-year-olds. It’s important to focus on abstinence.” Abstinence, Solenni notes, would prevent not just HPV, but an array of other sexually transmitted infections, including gonorrhea, chlamydia, and HIV.

Many find the idea of incorporating the vaccine into school-entry requirements particularly troubling. “We need to look at this with a serious moral perspective and talk about it some more instead of just imposing it on every parent and every child,” says Wendy Wright, senior policy director of Concerned Women for America . “We’re not saying don’t make this vaccine available.” But, she adds, giving the vaccine at an early age sends a message. “What they’ve done is told this 12-year-old, ‘You can now become sexually active,’” she says. “Perhaps they could adjust this vaccine so that it could be taken at a later age.” Solenni concurs, saying that although she still wouldn’t endorse it, the vaccine would best be offered only to people who are at least 18 years old. The only form of prevention she supports is abstinence from any sex outside marriage.

As a public health policy, delaying vaccination until age 18, an age before which many girls have become sexually active, fails. “In our study, we found that effectiveness was OK until age 15; then it decreased,” says Duke’s Myers. “It’s clear that waiting until 18 would reduce the overall benefits of the vaccine by a substantial proportion. I strongly doubt that those teens who aren’t having sex are being held back by a fear of HPV, and that being vaccinated would suddenly change behavior.”

One notable exception to the abstinence only refrain of the family-values groups is Focus on the Family. Reginald Finger, a public health physician and the medical issue analyst for the organization , serves on the CDC’s Advisory Committee for Immunization Practices. “If three doses of HPV vaccine is going to produce efficacy over a young-adult lifetime, then [age 12] might be a good time to reach them, just because they’re easier to reach and you can implement a system for doing that with the adolescent visit,” he says. “I do not think that you necessarily need to infer that if you’re giving it to 12 year olds, that 12 year olds are suspected to be at risk right then.” HPV, he notes, can be a long-lasting infection, to the point that it may be a risk even to people who have been abstinent until marriage. “With HPV, you could have a person in their 20s, never sexually active before marriage, marrying someone who has had a sexual history in their teens, who has turned around their lifestyle and had been abstinent for eight years,” he says. “Then all of a sudden, you have a situation where it’s possible HPV could be an issue.”

Both Merck’s Barr and Dartmouth ‘s Harper are optimistic that education may help change the perspectives of some of the more conservative groups. “The key thing is that neither Merck nor any other organization is interested in promoting sexual activity among adolescents, but we are interested in promoting the public health,” says Barr. Although HPV is transmitted sexually, it is as common as any other disease for which people are vaccinated, with approximately 5.5 million cases in the United States every year; the lifetime risk of HPV infection approaches 70 percent.

Ultimately, Barr says, “I think that parents, regardless of their political, religious, or cultural background, want to prevent cancer in their kids.” While that is undoubtedly true, a divide remains about whether vaccination or teaching only abstinence is the best way to do that.

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