(CINCINNATI) -- Vaccinating teenage girls against the human papillomavirus or HPV may be too little too late, according to a new study that found more than half of girls 13 and older already have the infection.
The three-dose vaccine, proven to slash the risk of HPV infection -- the number one risk factor for cervical cancer -- is recommended for 11- and 12-year-old girls, according to the U.S. Centers for Disease Control and Prevention. But some doctors delay the shots, thinking pre-teens have a low risk for the sexually transmitted infection.
"It really is important for physicians to offer the vaccine as recommended to girls that are 11 and 12 years old," said Dr. Lea Widdice, assistant professor of adolescent medicine at Cincinnati Children's Hospital Medical Center and lead author of the study, published Tuesday in the Archives of Pediatric and Adolescent Medicine. "The vaccine is very safe and highly effective, but it works best if we can give it to girls and boys before they're sexually active."
Widdice and colleagues tested 259 young women aged 13 to 21 for HPV during clinic visits for their first vaccine doses. Among 190 who were sexually active, 70 percent were already infected.
"The vaccine can only prevent the infection," said Widdice, warning that the vaccine cannot cure someone who's already HPV-positive.
Even girls who had sexual contact without intercourse were at risk, with 11 percent testing positive for the virus.
"HPV is different from other sexually transmitted infections in that it appears to be transmitted a lot more easily," said Widdice. "Although it's most efficiently transmitted through sexual intercourse, it can definitely be transmitted through genital skin-to-skin touching."
The study adds to mounting evidence that early vaccination can curb HPV infection, which beyond cervical cancer is also linked to genital warts and cancers of the vulva, vagina, penis, anus and throat.
"It supports the recommendation that the HPV vaccine be given to girls when they're 11 and 12 years old," said Widdice.
The CDC also recommends the vaccine for boys and men aged 9 through 26.
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