CDC Updates Recommendations on HPV Vaccine
, by NCI Staff
Adolescents younger than age 15 need only two doses of the human papillomavirus (HPV) vaccine, given at least 6 months apart, instead of three doses, according to new recommendations from the U.S. Centers for Disease Control and Prevention (CDC) and the Advisory Committee on Immunization Practices (ACIP).
Teenagers and young adults between ages 15 and 26 and people with weakened immune systems who start the HPV vaccine series should still get three doses of the vaccine to prevent cancers associated with HPV infection, the CDC and ACIP said.
The CDC announced the new recommendations on October 19.
The updated recommendations are based on a thorough review of data from recent clinical trials showing that, in younger adolescents, two doses of the vaccine produced an immune response similar to or greater than that produced by three doses among adult women in whom efficacy was demonstrated.
“The new recommendations are a great step toward raising vaccination rates in the United States,” said Aimée Kreimer, Ph.D., of NCI’s Division of Cancer Epidemiology and Genomics.
“A certain level of cost and inconvenience is involved in requiring three separate doses of the vaccine, so any way we can lower that barrier without sacrificing protection is an improvement. If adolescents are getting the necessary protection with less intervention, that’s a public health win.”
Room for Improvement
Certain types of HPV cause virtually all cervical cancers, and can cause a number of other cancers, including anal, oropharyngeal, vaginal, vulvar, and penile cancers.
In the United States, routine vaccination against HPV is recommended for 11- to 12-year-olds, for females through age 26 and males through age 21 who have not previously been vaccinated, and for men who have sex with men through age 26.
Yet a recent CDC analysis found that only about 63% of U.S. girls and 50% of boys 13 to 17 years old had started the HPV vaccine series during 2015. HPV vaccination rates—defined as having received at least one dose of the vaccine—improved substantially from 2014 to 2015 in boys (by 8.1%), according to the analysis, but increased only modestly for girls (by 2.8%).
Nevertheless, the rates of HPV vaccination continue to be substantially lower than the rates for other vaccines given routinely to boys and girls at age 11 or 12, such as the combined tetanus, diphtheria, and pertussis vaccine known as Tdap.
Research-Based Recommendations
The ACIP is a group of medical and public health experts that develops evidence-based vaccine recommendations for the United States. Recommendations from ACIP are forwarded to the CDC director for approval and then published as official guidelines by the CDC.
“In the past few years, randomized clinical trials have demonstrated antibody levels resulting from fewer than three doses of the vaccine that were not substantively different than antibody levels for three doses among the adult women in whom efficacy was proven,” said Dr. Kreimer, who serves as the NCI liaison with ACIP. Antibody levels are used as an indicator of immune response.
Dr. Kreimer added that adolescents had an especially strong immune response with only two doses of the HPV vaccine. Adolescents who received two doses of the vaccines had antibody levels that were equal to or higher than those of older teens and young women who received three doses.
CDC and ACIP recommended the two-dose vaccine series only for the younger age group because randomized clinical trials reported to date have not looked at the effects of a two-dose HPV vaccine series in older individuals.
The two doses of the HPV vaccine should be given at least 6 months apart, and ideally within 12 months, they advised. CDC will publish more detailed HPV vaccination guidelines for health care providers, parents, and insurers.
The new recommendations followed the October 7 approval by the Food and Drug Administration (FDA) of a two-dose regimen of the HPV vaccine Gardasil 9 for boys and girls ages 9 to 14 years old. Gardasil 9 protects against infection with nine types of HPV, including seven cancer-causing HPV types and two HPV types that cause genital warts.
The FDA approval was based on results of a clinical trial funded by Merck, which manufactures Gardasil 9. The trial showed that a two-dose regimen of the vaccine in 9- to 14-year-olds produced an antibody response similar to or greater than that produced by a three-dose regimen in 16- to 26-year-old women.
Although the CDC announcement did not specify a particular HPV vaccine, as of Oct. 31 Merck is no longer marketing its older quadrivalent Gardasil vaccine , which protects against infection by four HPV types, in the United States. And GlaxoSmithKline—which manufactures Cervarix , an HPV vaccine that protects against two high-risk HPV types—announced in October that it will no longer sell its vaccine in the United States.
“HPV vaccination protects against multiple cancers in men and women for which other means of prevention are not available,” Dr. Kreimer said. “It’s a very safe vaccine. The public health benefits of this vaccine are clear.”