Vaccinating both girls and boys against HPV is more effective, new study shows

When the human papillomavirus (HPV) vaccine was first recommended in 2006, it was only approved for girls, with strong messaging that the shot helped prevent certain forms of cervical cancer and other cancers caused by the infection. Even though the HPV vaccine was later approved for boys, uptake has been lower in this group.

Now, a new study suggests that the HPV vaccine is most effective at preventing cervical cancer when it's given to girls and boys, underscoring the importance of vaccinating both groups. But why should boys and girls get the HPV vaccine and what should parents take away from this? Experts break it down.

What the study says

The study, which was published Nov. 8 in the journal Cell, Host and Microbe, found that giving girls and boys the HPV vaccine creates "herd immunity" against certain forms of HPV, which can help lower the risk that girls will develop cervical cancer.

What are the key findings?

For the study, researchers studied 33 towns in Finland, which were randomly assigned to vaccinate boys and girls against HPV, to just vaccinate girls or to not offer the HPV vaccine to children. The study tracked more than 11,000 kids who were born between 1992 and 1994, and followed up with them when they were 18, as well as 5,500 people who researchers followed up with when they were 22.

The researchers discovered that eight years after the children were vaccinated, the prevalence of HPV types 16 and 18 —which are responsible for 70% of cervical cancers and are targeted by the vaccine — declined significantly in the 22 towns where it was given. In the 11 towns that only vaccinated girls, there was also a drop in HPV type 31 (linked to higher risk of head and neck cancers), while the 11 towns that vaccinated both girls and boys saw a drop in both HPV types 31 and 45 (the third most common type linked to invasive cervical cancer).

"By vaccinating both boys and girls, you will gain the benefit of herd protection for the community apart from the direct vaccine-induced immune protection," lead study author Ville Pimenoff, a senior research fellow at the Karolinska Institutet, tells Yahoo Life. Pimenoff says his findings show it would take 20 years of vaccinating only girls to get the same effect of lowering rates of cancer-causing HPV that could be achieved in just eight years of having both boys and girls vaccinated.

What experts think

Doctors applaud the findings. "This study is exciting and shows that both genders should be vaccinated in order to prevent cervical cancer," Dr. Andrea Milbourne, professor of gynecologic oncology and reproductive medicine at The University of Texas MD Anderson Cancer Center, tells Yahoo Life.

Milbourne says the study results back up a similar study conducted in Australia that found genital warts decreased, even in unvaccinated teens, when boys and girls were both given the HPV vaccine. Certain types of HPV can also cause genital warts, indicating that the vaccine helped better control the virus in the communities where it was used, Milbourne explains. "It takes many years from initial infection to cervical cancer," she says. "Genital warts, however, have an incubation period of weeks."

Dr. Danelle Fisher, a pediatrician and chair of pediatrics at Providence Saint John’s Health Center in Santa Monica, Calif., tells Yahoo Life: "HPV is so contagious. It makes perfect sense that, if we vaccinate both boys and girls, we will see improved infection rates."

But doctors stress that HPV vaccination benefits boys, too. "It's important to remember that males are also at risk of HPV-related cancers," Susan Vadaparampil, associate center director of community outreach, engagement, and equity at Moffitt Cancer Center, tells Yahoo Life. Boys are particularly at risk of oropharyngeal cancers (aka head and neck cancers), and cases of these cancers are increasing in men in the U.S., she points out.

"This comes up a lot in my office," Fisher says. "The HPV vaccine is not just to protect girls. When I have a girl in the office, it's really easy to talk about cervical cancer risk and rates. When I have a boy there, it's a little tougher of a sell, given that the vaccine was originally approved for girls. But there is a chance that HPV will affect these boys, too, as they grow up."

Why it matters

HPV vaccination in the U.S. isn't as high as experts would like it to be. In 2021, nearly 59% of teens between the ages of 13 and 15 had received two or three doses of the vaccine as recommended. (The National Cancer Institute has set a goal of having 80% of teens vaccinated against HPV by 2030.)

Vaccination rates are also lower in boys than in girls: Data show that vaccination rates are around 20 to 30% for boys aged 13 to 17, and 10 to 15% for men aged 18 to 26.

But Pimenoff stresses that the HPV vaccine is the "best way" to prevent genital and oral cancers caused by HPV. Fisher agrees. "This is an anti-cancer vaccine," she says, adding that she urges parents to talk to their child's pediatrician about vaccination.

"It is a tremendous missed opportunity for medical and public health professionals if we don’t use this compelling data to continue to encourage HPV vaccination," Vadaparampil says.