(CNN) — Young people who get the human papillomavirus vaccine before turning 15 need only two doses, rather than three, the Centers for Disease Control and Prevention announced last week.
It recommends that children ages 11 and 12 receive two doses of the HPV vaccine at least six months apart; 13- and 14-year-olds may also use this schedule. People who start the series at 15 through 26 still need three doses, it said.
HPV is a common virus that can affect anyone who is sexually active. It can result in HPV-related cancers, with cervical cancer most common among women and oropharyngeal cancers most common among men.
The vaccine is recommended routinely for women through the age of 26 and men through the age of 21, said Dr. Melinda Wharton, director of the CDC’s Immunization Services Division. Gardasil 9, approved in 2014, prevents HPV types that cause cervical cancer, vaginal and vulvar cancer in females, anal and throat cancer in females and males, penile cancer in males and genital warts in males and females.
In 2006, the Food and Drug Administration licensed the HPV vaccine at three doses to be administered over six months. Additional studies since then showed that, for people ages 9 to 14, two doses of the vaccine can be just as effective.
The CDC and its Advisory Committee on Immunization Practices reviewed clinical trial data that found two doses of the HPV vaccine in young adolescents ages 9 to 14 produced an immune response similar to or higher than that of young adults age 16 to 26 who received three doses.
“The immune response to the vaccine is better in the younger age groups than the older age groups,” said Dr. Yvonne A. Maldonado, vice chairwoman of the American Academy of Pediatrics Committee on Infectious Diseases and professor of pediatrics at the Stanford University School of Medicine.
For people younger than 15, Wharton said, the second dose should be taken six to 12 months after the first.
“This allows families to have their child vaccinated at the annual visit, which should make it easier to complete these series,” she said.
Maldonado predicts that a two-dose schedule, rather than three, will also make it easier to complete the series.
“Only 42% of teenage girls and 20% of teenage boys have gotten all three doses,” she explained. “We know that the numbers would be higher for just one dose.”