Unique to Women
In 2006, the FDA approved the use of Gardasil, the first vaccine designed to prevent cervical cancer. FDA approval of Cervarix followed four years later. Both vaccines are highly effective against two types of HPV known to be associated with cervical cancer. Gardasil also protects against two other HPV types associated with genital warts (see p. 298). Newer HPV vaccines are being designed to protect against more HPV types.
Gardasil’s introduction was highly controversial, because its manufacturer (Merck) initially lobbied some states for school mandates, which would require vaccine distribution in certain grades. Because the vaccine is so much less effective if administered after exposure to HPV, and because so many girls have their first sexual experience in their early teen years (when exposure to HPV is highly likely), these mandates were proposed for girls eleven to twelve years old.
Some parents objected strongly to these proposed mandates. Media coverage portrayed the objections as coming mostly from socially conservative groups and individuals, yet many parents who actively support school-based comprehensive sex education also objected primarily because the vaccine was tested mostly in older girls and women (age fifteen to twenty-five) instead of the group to which the vaccine is marketed. Only a few hundred girls in the eleven- to twelve-year-old range were included in the clinical trials that led to approval of the vaccine. Parents understandably wanted more evidence of safety before seeking the vaccine for their daughters. As of 2011 millions of young girls have been vaccinated with Gardasil and Cervarix, so five-year safety profiles for the vaccine will soon be available.
Even the chair of the CDC Advisory Committee on Immunization Practices pointed out that a school mandate for this vaccine was not appropriate when it was initially introduced. First, although genital HPV infections cause nearly all cervical cancer, they are not transmitted by person-to-person contact normally encountered in typical school or classroom settings. Simply sitting next to a student with an HPV infection will not transmit the HPV virus. Intimate contact is required. Second, new vaccines are generally introduced more slowly—not with universal school mandates—to determine what kinds of problems may emerge that need to be considered before rolling out a new vaccine campaign for a very large population.
Disparities in Access
Most women who die of cervical cancer never had regular Pap tests, had false-negative results, or did not receive proper follow-up.
In the United States, socioeconomic and racial disparities are evident in statistics for cervical cancer. Vietnamese immigrants are five times more likely to be diagnosed with cervical cancer than white women. African-American and Native American women are twice as likely to die of the disease as are white women. In one study, Hispanic women had about twice the cervical cancer incidence of non-Hispanic women in border counties near Mexico.16 Disparities are due, at least in part, to women of color having less access to Pap screening. It is quite possible that those women with the highest rates of cervical cancer will also have less access not only to Pap screening but also to the HPV vaccine. Until our health care system addresses such disparities in access, girls and women likely to benefit the most from this vaccine may well not be able to choose it.
To ensure more equal access to any adolescent vaccine, adequate infrastructure and resources must be made available. Some recommend implementation of school-based adolescent immunization programs similar to those formerly in place for delivery of hepatitis B vaccines. The United Kingdom and Australia have volunteer, nationally supported school-based campaigns that have resulted in high HPV vaccine coverage for about 70 percent of teenage girls.
Currently, school-based health programs and routine preventive care visits for adolescents are limited in the United States, making it highly difficult to provide good access to HPV vaccines, especially the type of access needed to ensure all three required vaccine doses are administered. Available data suggest HPV vaccine coverage in the United States is low (less than 50 percent) and the proportion of girls receiving all three doses of HPV vaccine is even lower (less than 25 percent).
Pap Tests Essential for Prevention and Treatment
HPV vaccines do not protect against all types of HPV associated with cervical cancer. Thus, regular Pap tests among sexually active women remain essential for cervical cancer prevention. Resources should not be diverted away from Pap screening programs to pay for the unusually expensive cervical cancer vaccine. Because Merck marketed Gardasil with a campaign that unnecessarily frightened girls, young women, and parents, many people now have a distorted view of this disease, the vaccine, and the continued importance of Pap screening.
There is no question that HPV vaccines represent an important scientific advance in the field of vaccine research, but exaggerating their potential benefit in places such as North America will not serve us well. In countries where there is little or no access to Pap screening, current HPV vaccines might have much more potential for saving lives if their costs were reduced considerably and if adequate infrastructure to provide them responsibly were securely in place.
Important questions will be answered over time as use of the HPV vaccine expands and improved vaccines are developed. For example, will successful prevention of infections and disease caused by the types of HPV targeted by this vaccine be replaced by disease caused by other HPV types, which now account for a smaller percentage of cervical precancer and cancer? Are three doses of vaccine required for long-term protection? Will booster shots be needed to maintain protection throughout adulthood? If so, how many? What rare complications associated with these vaccines might be identified as more young women use the vaccine over time?
As with all drugs and vaccines, longterm surveillance supported by the FDA and drug companies is essential.
Excerpted from the 2011 edition of Our Bodies, Ourselves. © 2011, Boston Women's Health Book Collective.
16. S. S. Coughlin et al., “Cervical Cancer Incidence in the United States in the US‑Mexico Border Region, 1998–2003,” Cancer 113 (2008): 2964–73.
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