Department of Health and Human Services (HHS) announced major changes to the childhood vaccine schedule. The new guidance reduced the number of universally recommended vaccines from 17 to 11. The HPV vaccine is still recommended for all children aged 11 or 12. However, the new guidelines suggest that people only need one vaccine instead of two or even three. Experts say this change in the HPV program reflects what research has shown.

When the HPV vaccine was first introduced, it was given in three doses months apart. This has changed in recent years. Real-world research found that two doses worked equally well. The World Health Organization, the Advisory Committee on Immunization Practices (ACIP) and the Centers for Disease Control and Prevention (CDC) say most young people only need two shots. But newer research says just one dose may be enough.

This new research comes from the ESCUDDO triala research study comparing the effectiveness of one HPV vaccine dose with two. The results were published in New England Journal of Medicine in December 2025. For the study, researchers enrolled more than 20,000 girls aged 12-16 in Costa Rica since 2017. The girls were randomly assigned to one of four groups.

• The first group received one dose of Cervarix, a vaccine that protects against the two types of HPV (16 and 18) that cause about 70% of all cervical cancer.
• The second group received two doses of Cervarix. (Cervarix is ​​no longer available in the United States, but is still used in other countries.)
• The third group received one dose of Gardasil 9, which protects against the 9 types of HPV most likely to cause cancer or genital warts.
• The fourth group received two doses of Gardasil 9. (Gardasil 9 is the only HPV vaccine available in the United States.)

The vaccines were more than 97% effective in all four groups. The researchers concluded that one vaccine was as good as two in protecting against HPV types 16 and 18. Gardasil 9 protects against these and seven other types of HPV that cause genital warts or other types of cancer. HPV has been linked to cancer of the penis, vulva, anus and throat.

A similar randomized trial from Kenya found that one dose of Gardasil 9 or Cervarix was 98% effective in preventing HPV 16 and 18.

This is good news. Switching to a single dose of the HPV vaccine could help increase vaccine uptake. It will remove some of the barriers, such as transportation and time off work, that prevent some people from returning for additional doses. It will also make large-scale vaccination efforts easier and more affordable, especially in low-resource countries.

But the American Academy of Pediatrics (AAP) has not changed its recommendations. The AAP is the membership group for pediatricians. Experts worry that this could cause some confusion. Many physicians look to the AAP for guidance when deciding what to do in their own practice.

Experts are also concerned that HHS made this change behind closed doors. Normally, changes in vaccine regimens and doses are made by an advisory committee. And the public is usually able to comment before the CDC makes a final decision.

In addition, some of the other vaccine schedule changes announced at the same time were not based on science. Experts suggest parents turn to their pediatrician for advice on which vaccines (and how many doses) will keep their children safe.