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NIH Study: HPV Vaccine May Benefit HIV-Infected Women
Healthcare providers shouldn’t withhold vaccination, researchers say (Nov. 8)
Women with human immunodeficiency virus (HIV) infection may benefit from a vaccine for human papillomavirus (HPV) infection, despite having already been exposed to HPV, a study finds.
Although many women may have been exposed to less serious forms of HPV, more than 45% of sexually active young women who have acquired HIV infection appear never to have been exposed to the most common high-risk forms of HPV, according to the study from a National Institutes of Health (NIH) research network.
HPV infection is the most common sexually transmitted infection in the world. The virus can infect the anal and genital areas, mouth, and throat of males and females. High-risk forms of the virus can cause cancer, including cancer of the cervix.
The researchers noted that earlier studies had found that many HIV-infected women were more likely than noninfected women to have conditions associated with HPV, such as precancerous conditions of the cervix, as well as cervical cancer.
"Healthcare providers may hesitate to recommend HPV vaccines after a girl starts having sex," said lead author Jessica Kahn, MD, MPH. "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."
The Centers for Disease Control and Prevention (CDC) recommends HPV vaccination for girls and young women aged 11 to 26 years. If an individual has not been exposed to the virus, approved HPV vaccines can protect against four virus types. Two HPV types — HPV-16 and HPV-18 — cause 70% of cervical cancers. Two others — HPV-6 and HPV-11 — cause 90% of genital warts.
At the time the women in the study received their first HPV vaccination, the researchers found that 12% had an existing HPV-16 infection and that 5% had an HPV-18 infection. Because of their HIV status, these women may have been more likely to develop cervical cancer or to develop a cancer that is hard to treat, the researchers said.
“Cervical cancer screening for sexually active young women is an important clinical priority, but our findings suggest it is especially so for women at risk of HIV,” said study co-author Bill G. Kapogiannis, MD.
The findings appear in the Journal of Acquired Immune Deficiency Syndromes.
The researchers analyzed blood and tissue samples from 99 HIV-positive women aged 16 to 23 years who had received an initial vaccination for HPV infection. The researchers examined the samples for evidence of an existing HPV infection as well as for previous exposure to the virus.
The researchers tested for the presence of 41 of more than 100 existing types of HPV virus, including 13 high-risk types. They found that 75% of the women had an existing HPV infection with at least one type of virus, and that 54% tested positive for a high-risk type. However, when examining the two types that cause 70% 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.
When the researchers tested for each type of HPV individually, they found that nearly 75% of the women did not have a current HPV-18 infection or evidence of previous exposure. For HPV-16, 56% of the women did not have a current infection or previous exposure.
“Even among women who test positive for one type of HPV, the vaccine may effectively prevent infection with others — especially high-risk forms that cause cancer,” Kahn said. “It’s important that doctors don't withhold the vaccine in these cases, thinking that it's too late for a vaccine to be effective.”
Source: NIH; November 8, 2012.