One-dose HPV vaccine plan gains ground as US guidance fractures

Research suggests a single HPV vaccine dose can provide lasting protection, but US officials and medical groups remain divided while evidence for boys and non-cervical cancers is still limited.

Paediatricians and vaccine specialists are increasingly considering a question that would have seemed unlikely only a few years ago: whether one dose of the human papillomavirus vaccine may be enough for some children. The discussion reflects both new evidence and a wider upheaval in US vaccine policy, where official guidance and the positions of medical organisations have become more fragmented. Jason Schwartz, a Yale University vaccine policy researcher, told the Associated Press that any move away from the long-standing two-dose approach would mark a major change in what families have been told for years. According to the CDC, HPV vaccination is still routinely recommended at ages 11 or 12, with the option to begin at age 9.

HPV, or human papillomavirus, is the most common sexually transmitted infection in the United States and is linked to cancers of the cervix, anus, penis, vulva, vagina and throat. The CDC says the virus is responsible for most cervical cancer and a large share of anal cancers, while the agency’s clinical overview also connects HPV to oropharyngeal cancers. Federal health officials first approved an HPV vaccine in 2006, and the campaign has since become one of the strongest examples of cancer prevention through immunisation.

The dosing schedule has already changed once before. When the vaccine was introduced, girls were advised to receive three shots, and boys were added later as part of efforts to reduce transmission and lower cancer risk across the population. In 2016, federal guidance moved to two doses for younger adolescents after studies showed that a smaller number of injections still produced strong protection when spaced apart. The CDC continues to recommend two doses for children who begin the series before their 15th birthday, and three doses for older adolescents and immunocompromised patients.

The new interest in a single-dose schedule has been driven by evidence that has accumulated over several years. A study funded by the National Institutes of Health and published in the New England Journal of Medicine followed more than 20,000 girls in Costa Rica and found that one dose was at least 97% effective at preventing persistent HPV infection, a key step towards reducing cervical cancer. The University of Minnesota’s Vaccine Integrity Project also reviewed recent research and concluded that HPV vaccination lowers the risk of genital-area cancers in women, while a study published in JAMA Oncology found vaccinated men were nearly 50% less likely to develop cancers of the head and neck, oesophagus, anus or penis. Angela Ulrich, who led the review, said the protection appears to last for decades.

That evidence has prompted policy debate. According to the AP, Robert F. Kennedy Jr., now US health secretary, ordered a reduction to a one-dose schedule in January as part of a broader rewrite of childhood vaccination guidance, although a federal judge blocked that move. The CDC advisory committee had also begun examining whether recommendations should be revised, but that work was interrupted when Kennedy dismissed the panel’s members. The American Academy of Pediatrics, which has its own immunisation schedule, has been reviewing whether one dose may be adequate for some children and whether the best age to start may also change.

For now, the official advice remains two shots for most younger adolescents, and experts stress that getting vaccinated matters more than waiting for the science to settle every remaining question. There is solid evidence for single-dose protection against cervical cancer in girls, but far less information on whether one dose gives enough protection against other HPV-related cancers, especially in boys. Doctors also note that HPV shots can be more painful than some other routine vaccines, which can make hesitant families more reluctant to return for a second appointment. Still, Scott Hadland, who treats adolescents and young adults at a Boston clinic, said the benefit is straightforward: “It prevents cancer.”