Key takeaways:
- Uptake of HPV vaccines has decreased in recent years.
- The effectiveness of one dose of either bivalent or nonvalent HPV vaccines was noninferior to receiving two doses.
A single dose of either bivalent or nonvalent HPV vaccine was just as protective as the standard two doses of either vaccine in preventing HPV16 or HPV18, according to a study published in The New England journal of Medicine.
“persistent HPV infection can cause cervical cancer, and 77% of the global burden of cervical cancer is attributable to HPV types 16 and 18,” Aimée R. Kreimer, PhD, a senior investigator in the National Cancer Institute’s Division of Cancer Epidemiology and Genetics, and colleagues wrote.

Data derived from Kreimer AR, et al. N Engl J Med. 2025;doi:10.1056/NEJMoa2506765.
“HPV vaccination could prevent most cervical cancers, but access remains inadequate: nearly 20 years after recommendation by WHO, only 27% of adolescent girls worldwide have been vaccinated,” they wrote.
In the United States, the CDC has recommended for 20 years that children receive two or three doses of HPV vaccine by age 11 or 12 years. Under the new childhood immunization schedule announced by HHS on Jan. 5, though, the CDC now recommends just one dose given at age 11 or 12 years — a change that HHS attributed to “recent scientific studies” showing that one dose is as effective as two doses.
Research has shown that extending vaccination to an earlier age — and promoting the vaccines’ ability to prevent cancer — can increase uptake, which has declined in the U.S. over the last few years.
One study showed that 62.6% of adolescents were up-to-date on HPV vaccinations in 2022 — marking the first time in a decade that HPV vaccine coverage did not increase among U.S. teens. Just 61.4% were up-to-date in 2023.
According to Kreimer and colleagues, emerging data suggest a single dose — which WHO has recommended in an effort to increase coverage — may provide protection, although they said whether it would provide similar protection to two doses “uncertain.”
To assess the effectiveness of one vs. two doses, the researchers enrolled 20,330 girls aged 12 to 16 years and randomly assigned them in a 1:1:1:1 ratio to receive one or two doses of a bivalent HPV vaccine or one or two doses of a nonavalent HPV vaccine. According to the study,the researchers followed study participants for 5 years to track new HPV16 or HPV18 infections occurring from month 12 to month 60 and persisting for at least 6 months.
Results showed that one dose of the bivalent vaccine was 98.2% (95% CI, 96.1%-99.6%) effective and one dose of the nonvalent vaccine was 97% (95% CI, 94.3%-99.1%) effective vs. two doses of either vaccine (97.8% and 98.5% effective, respectively).
Additionally, although the trial was not meant to evaluate safety, the researchers noted that no safety concerns were identified, with just seven of the more than 20,000 participants reporting serious adverse events “possibly, probably or definitely” related to the HPV vaccination over the 5-year study period.
In an accompanying editorial, Ruanne V. Barnabas, MB, ChB, DPhil, of Massachusetts General Hospital and Harvard Medical School, said the findings were “the strongest evidence to date” to support the WHO recommendation that girls and young women up to age 20 get one or two doses of the HPV vaccine.
“The WHO strategy for cervical cancer elimination sets ambitious but achievable targets: 90% of girls fully vaccinated with the HPV vaccine by 15 years of age, 70% of adult women screened with a high-performance test, and 90% of women with disease receiving appropriate treatment,” Barnabas wrote, adding that one-dose vaccination strengthens efforts made to meet these goals.
“We have the evidence and tools to eliminate cervical cancer. What remains is the collective will to implement them equitably, effectively and now,” she wrote.