A new study on human papillomavirus (HPV) finds that Black women are more likely than their white counterparts to be infected with strains of the virus that are not covered by the two currently available vaccines. Nonetheless, the researchers note that it is important for Black parents to get their children vaccinated while drug companies work to make new vaccines that cover additional strains.
HPV is actually a group of over 150 related viruses that can infect various parts of the body. There are 40 strains of the virus that are known to be spread through sexual activity and can infect the male and female genitals as well as the head, neck, throat, and anus. Some of these strains—including strains 6 and 11—can cause genital warts, while others, if left untreated, can lead to cancer of the genitals or cervix. Researchers have identified some 13 strains that can cause cancer and have determined that strains 16 and 18 likely cause 70 percent of all cervical cancers.
There are currently two vaccines on the market that can prevent infections with certain strains of HPV. Cervarix, made by GlaxoSmithKline, protects against strains 16 and 18. Gardasil, made by Merck, protects against 6, 11, 16, and 18.
Though these are the strains known to cause most cases of genital warts and cervical cancer, the new research, which was presented Monday at an international conference, shows that they are not the strains most likely to infect Black women. Researchers at Duke University looked at 516 women who were being sent for additional testing after having an abnormal pap smear. (A pap smear is a test that collects cells from the surface of the cervix and can detect precancerous or cancerous changes in these cells.) More than 70 percent of the women were infected with HPV and most had more than one strain of the virus. Which strains these were, however, varied by race. White women were most likely to have strains 16, 18, 31, and 45, while Black women were more likely to have strains 33, 35, 58, and 68. Though responsible for fewer cases of cervical cancer than strains 16 and 18, all four of the strains affecting Black women can cause cancer. For example, a meta-analysis estimated that strain 33 caused 4 percent of squamous cell cancer of the cervix (the most common kind of cervical cancer) while strains 58, 35, and 68 caused 3 percent, 2 percent, and less than 1 percent of this kind of cancer, respectively.
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Catherine Hoyo, one of the researchers on the study, told NBC News, “It looks like we have different strains by race.” She added, “African-American women are about 20 percent more likely to develop cervical cancer and almost twice as likely to die from the disease compared with non-Hispanic white women.”
Merck is developing a new vaccine that will provide protection against some but not all of the strains seen in the African-American women. Specifically, the new vaccine will continue to cover strains 6, 11, 16, and 18, and add protection against strains 31, 33, 45, 52, and 58.
HPV is very common. The Centers for Disease Control and Prevention estimates that over 79 million people in the United States currently have the virus and that there will be 14 million new infections each year. HPV does not cause long-term health problems in most people, as the body can often clear itself of the virus. Pap smears and HPV tests can also detect infection and precancerous changes to cervical cells, which can be treated before they become cancer. Still, approximately 10,000 women get cervical cancer each year and more than 15,000 additional men and women get cancers of the head, neck, throat, genitals, or anus caused by HPV.
The vaccines represent a huge advance in cancer prevention and as such are recommended as part of routine immunizations for 11- and 12-year-olds. While this study points to the need for advances in the vaccine to cover more strains of the virus, the researchers caution that this is not a reason for Black parents to delay vaccinating their kids. As Hoya told NBC News, “I would do it now and do it again with the new vaccine.”