The HPV vaccine is far more effective than expected, with benefits extending beyond those who receive the vaccine, a study published Wednesday finds.
The new study, published in The Lancet, suggests that the more people who receive the vaccine, the better. That’s because vaccination not only reduces rates of HPV infection and the presence of precancerous cells in the cervix in people who receive the vaccine, it also reduces rates of HPV-related diseases in people who were not vaccinated.
The findings come as a U.S. federal advisory panel recommended Wednesday that the HPV vaccine be given to both men and women up to age 26.
HPV, or human papillomavirus, is the leading cause of cervical cancer. The virus can also cause other cancers, including cancers of the penis, head and neck, as well as conditions like genital warts.
The HPV vaccine was first introduced in 2006. Since then, more than 115 countries and territories have implemented it in their vaccination programs. The World Health Organization recommends that girls ages 9 to 13 receive two doses of the vaccine.
“The impact of the HPV vaccination has actually exceeded expectations,” said Lauri Markowitz, associate director of science for HPV at the Centers for Disease Control and Prevention, who worked on the study. “The trials showed that HPV vaccines are very effective, and data from the real world has confirmed that.”
Indeed, the reductions in HPV infections and precancerous cells “are a first sign that vaccination could eventually lead to the elimination of cervical cancer as a public health problem,” the study’s lead author, Mélanie Drolet, an epidemiologist at Laval University in Canada, said in a statement.
The Lancet study expanded upon a 2015 meta-analysis that had looked at the real-world effects of the vaccine. The new analysis was updated to include a total of 65 studies, which spanned eight years and included more than 60 million people living in 14 countries. Each study measured either changes in the number of new HPV infections, genital warts diagnoses or cases of abnormal cells associated with cervical cancer in countries before and after they adopted routine HPV vaccination in girls. (Two countries included in the analysis, the U.S. and Australia, also recommend the vaccine for boys.)
The impact of the HPV vaccination has actually exceeded expectations.
The researchers found that, in these countries, there was a significant decrease in the prevalence of two strains of HPV that cause 70 percent of cervical cancers, HPV 16 and 18. (There are more than 100 strains of HPV, 14 of which are known to cause cancer. The HPV vaccine protects against up to 9 strains.) In addition, there was a decrease in the prevalence of precancerous cells in the cervix, which can develop into cancer.
What’s more, in countries where at least half the population that was targeted for vaccination had actually received the vaccine, researchers saw evidence of herd immunity, meaning there was a decrease in the prevalence of HPV-related diseases even among those who weren’t vaccinated. This is because vaccination leads to fewer HPV hosts.
These countries also saw a decrease in genital warts diagnoses among unvaccinated boys and older women. And among girls within the age groups targeted for vaccination, there were fewer diagnoses of three HPV strains that the vaccine does not specifically protect against, a phenomenon called cross-protection. Countries in which people in multiple age groups received the vaccine also saw a greater decrease in HPV-related disease.
“This paper shows that with a broader age range that’s targeted, you’ll find greater impact in your vaccination program,” Markowitz told NBC News.
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