The childhood vaccine schedule underwent significant changes recently, with the Department of Health and Human Services (HHS) reducing the number of universally recommended vaccines from 17 to 11. Among these adjustments is a potential shift in the recommended dosage for the human papillomavirus (HPV) vaccine, raising the question: is one shot of the HPV vaccine enough? New guidance suggests a single dose may provide sufficient protection, a change driven by evolving research and offering potential benefits for vaccine uptake.
For years, the HPV vaccine regimen involved multiple doses. Initially, three doses were administered over several months. More recently, research demonstrated that two doses were equally effective for most individuals. The World Health Organization, the Advisory Committee on Immunization Practices (ACIP), and the Centers for Disease Control and Prevention (CDC) currently recommend two doses for many young people. However, the latest findings, published in December 2025, suggest that a single dose could be sufficient to protect against HPV-related cancers, and diseases. This shift in thinking regarding the HPV vaccine is based on robust clinical trial data.
The ESCUDDO Trial: Evidence for Single-Dose Effectiveness
The impetus for considering a single-dose HPV vaccine schedule comes from the ESCUDDO trial, a comprehensive research study comparing the effectiveness of one versus two doses. Researchers enrolled over 20,000 girls aged 12-16 in Costa Rica beginning in 2017. Participants were randomly assigned to one of four groups, each receiving a different HPV vaccine regimen. The study, whose results were published in the New England Journal of Medicine, examined both Cervarix and Gardasil 9.
- The first group received one dose of Cervarix, protecting against HPV types 16 and 18, responsible for approximately 70% of cervical cancers.
- The second group received two doses of Cervarix. (Cervarix is no longer available in the United States but remains in use internationally.)
- The third group received one dose of Gardasil 9, which protects against nine HPV types linked to cancer and genital warts.
- The fourth group received two doses of Gardasil 9, currently the only HPV vaccine available in the United States.
The results were striking: all four groups demonstrated over 97% effectiveness. Researchers concluded that one dose of either vaccine was as effective as two doses in protecting against HPV types 16 and 18. Gardasil 9’s broader protection—covering nine HPV types—offers defense against genital warts and other cancers, including those of the penis, vulva, anus, and throat. A similar randomized trial conducted in Kenya too found that one dose of Gardasil 9 or Cervarix was 98% effective in preventing HPV 16 and 18.
Increased Access and Affordability
The potential move to a single-dose HPV vaccine schedule is expected to improve vaccine uptake by removing barriers to completion. Multiple doses can present logistical challenges, including transportation and time off from work or school. Simplifying the regimen could make vaccination more accessible, particularly in low-resource countries where large-scale vaccination campaigns are crucial. Reducing the number of doses also translates to lower costs, further enhancing accessibility.
Concerns and Conflicting Recommendations
Despite the promising research, the American Academy of Pediatrics (AAP) has not yet altered its recommendations. The AAP, a leading organization for pediatricians, continues to advocate for the two-dose schedule. This discrepancy has raised concerns among experts, who fear it could create confusion for both healthcare providers and patients. Many physicians rely on AAP guidance when making vaccination decisions for their patients, according to AAP News.
Adding to the concern is the process by which HHS announced these changes. Traditionally, adjustments to vaccine schedules are made through an advisory committee, allowing for public comment before the CDC finalizes any decisions. Experts have expressed concern that this process was bypassed, raising questions about transparency and the inclusion of diverse perspectives. Some experts also noted that other changes to the vaccine schedule announced concurrently were not supported by scientific evidence.
What In other words for Parents and Patients
Given the evolving recommendations and the differing guidance from the AAP, experts advise parents to consult with their pediatrician to determine the most appropriate vaccination schedule for their children. A personalized discussion can address individual risk factors and ensure informed decision-making. The HHS changes to the childhood vaccine schedule, including the potential for a single-dose HPV vaccine, underscore the dynamic nature of medical science and the importance of staying informed.
Disclaimer: This article provides information for general knowledge and informational purposes only, and does not constitute medical advice. This proves essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
The CDC and HHS are expected to provide further clarification on the new vaccine schedule and address concerns raised by medical professionals in the coming months. Parents and healthcare providers should monitor official updates for the most current recommendations.
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