The US Centers for Disease Control and Prevention calls for both girls and boys to be vaccinated against HPV, the sexually transmitted virus that causes cervical cancer.
Some parents and community groups have been concerned that the vaccine might promote risky sex.
But in the new study, even the small group of girls who misunderstood their risk of sexually transmitted infections (STIs) after getting vaccinated didn't change their behaviour as a result, researchers found.
"There are so many contributing factors to whether an adolescent decides to have sex or not, and whether they decide to limit their number of partners or use condoms," says Dr Jessica Kahn. "Getting a vaccine probably just plays a very, very small role in their decisions."
I was also interested by this:
"We've already seen rates of infection go down by 77 per cent, while genital warts have almost disappeared in young women and men," she says.
In other words, clear health benefits.