In October 2016, the Centers for Disease Control and Prevention (CDC) issued a recommendation that adolescents aged 9–14 need only two doses of the human papillomavirus vaccine at least six months apart, rather than the previously recommended three doses, to achieve immunity. Older adolescents and young adults aged 15–26 still need the recommended three doses of vaccine.

The new recommendation was based on findings from a review of clinical trials showing that two doses of the vaccine in younger adolescents aged 9–14 achieved an immune response similar to or higher than the response in young adults aged 16–26 who received three doses.

Also in October, the U.S. Food and Drug Administration (FDA) approved adding a two-dose schedule for 9-valent HPV vaccine for adolescents aged 9–14.