Doctors don't usually advise young women infected with HIV, the virus that causes AIDS, to have the vaccine for human papillomavirus. The thinking is that these women, who are already sexually active, probably have already been exposed to HPV. Therefore, the vaccine is unlikely to do any good.
That approach may be a mistake, according to research published in the Journal of Acquired Immune Deficiency Syndromes. In the study of HIV-positive women, researchers found that many are not infected with some of the most serious strains of HPV and could still benefit from vaccination.
HPV is the most common sexually transmitted virus. There are many strains of HPV, but four -- types 16, 18, 6 and 11 -- are linked to the development of disease. Types 19 and 19 account for about 70 percent of all cervical cancers while types 6 and 11 cause 90 percent of cases of genital warts. The vaccine protects against those four strains and is recommended for girls before they become sexually active, ages 11 through 26.
The new study, by Dr. Jessica A Kahn, an associate professor of pediatrics at Cincinnati Children's Hospital Medical Center, examined 99 HIV-positive women ages 16 to 23 receiving their first HPV vaccination. She found that 75 percent of the women had an existing HPV infection with at least one type, with 54 percent testing positive for a high-risk type. However, when examining the two types that cause 70 percent of cervical cancers (HPV-16 and HPV-18), the researchers found that nearly half of the women had no existing infection with either type and showed no evidence of exposure to them.
"Health care providers may hesitate to recommend HPV vaccines after a girl starts having sex," Kahn says. "However, our results show that for a significant number of young women, HPV vaccine can still offer benefits. This is especially important in light of their HIV status, which can make them even more vulnerable to HPV's effects."
Protection against developing cervical cancer is especially important in these women, she notes, because HIV status increases the risk of cervical cancer and makes it harder to treat.
HPV vaccination has only been available for about six years, and knowledge on the benefits of the three-shot series is still emerging. Another study, published this week in the Journal of Infectious Diseases found a significant decrease of HPV prevalence in Australia since that country implemented widespread vaccination.
Women ages 18 to 24 were examined with Pap screening throughout the country in the two years (2005-07) before vaccination became available and in the two years after (2009-10). There was a 20 percent overall decrease in genital HPV prevalence and a whopping 77 percent decrease in the targeted strains -- types 6, 11, 16 and 18 -- following the advent of the vaccine program.
Moreover, HPV was detected in only 5 percent of vaccinated women in the post-vaccine era compared to 15.8 percent in unvaccinated women in the post-vaccine era and 28.7 percent of women in the pre-vaccine years.
Question: Do you think enough people who are eligible for the HPV vaccine get the shots? Tell us what you think in the comments.
Shari Roan is an award-winning health writer based in Southern California. She is the author of three books on health and science subjects.