What to Know About One-dose HPV Vaccination

On January 5, 2026, the Deputy Secretary of Health and Human Services Jim O’Neill announced changes to the U.S child and adolescent recommended immunization schedules, stating, “recent scientific studies have shown that one dose of the HPV vaccine is as effective as two doses. The CDC is following the lead of several peer nations by recommending one instead of two doses of this vaccine.” Importantly, the updated recommendation did not provide guidance based upon the age of the patient at the time of vaccination. As of today, the Centers for Disease Control and Prevention (CDC) still details the recommendation as a two- or three-dose schedule, depending on the age at the initial vaccination.

Here’s the available evidence around a one-dose regimen:

• A paper published in the New England Journal of Medicine and primarily authored by researchers at the National Cancer Institute demonstrated one dose of either bivalent (HPV2) or nonavalent (HPV9) vaccine was noninferior to two doses in preventing HPV16 or HPV18 infection in Costa Rican females ages 12-16 years. Effectiveness was at least 97% in all four arms of the study: one dose or two dose HPV2, and one dose or two dose HPV9.
  • The study included nearly 20,000 girls but did not include girls older than age 16 or boys of any age.
  • The study followed participants for only 60 months, with assessments at months 54 and 60.
  • One dose was noninferior to two doses with respect to protection against seven carcinogenic HPV types, which account for approximately 95% of all cervical cancers.
  • The study did not look at outcomes beyond 5 years and did not look at non-cervical HPV-related cancers.
• Large, randomized studies in Kenya, India, and Tanzania showed one dose was as effective as two or three doses, even after 10 years or more. However, again, the studies were done only in women and looked only at cervical cancer outcomes.
• A large retrospective study involving more than 760,000 men from the U.S. demonstrated significant reduction in head and neck, anus and anal canal, and penis cancers in men who had been vaccinated against HPV compared to unvaccinated males, but did not compare outcomes based upon the number of HPV vaccine doses received.

The bottom line:

• While there is evidence that one dose of HPV vaccine may be as effective at preventing cervical cancers as two/three dose regimens, the available evidence does not include outcomes beyond 12 years from vaccination.
• There are studies that show reductions in non-cervical cancers, but there is currently no published data to confirm that one dose is as effective as two or three dose regimens in preventing these cancers.
• Countries that recommend a single dose of HPV vaccine tend to be low- and middle-income countries that make these recommendations based upon logistical and financial considerations.
• Denmark recommends 2 doses of HPV vaccine for girls.
• The United States does not have an HPV vaccine that is FDA-licensed for a one-dose regimen.