A cluster randomized trial presented at IDWeek 2026 supports starting HPV vaccination earlier than the standard recommendation. Among 62,271 children across 31 U.S. pediatric practices, those whose clinics introduced the vaccine at age 9 or 10 were significantly more likely to initiate and complete the two-dose series by age 13 than those whose clinics began at ages 11 or 12. Initiation reached 77.1% versus 67%, and completion reached 61.6% versus 45.1%.
The study's lead author, Sean O'Leary of Children's Hospital Colorado, said the results should encourage policymakers to consider a preferential recommendation for starting at ages 9 or 10. Current CDC guidance says vaccination can begin at 9 but recommends routine immunization at 11 or 12, while the American Academy of Pediatrics endorses starting anywhere from 9 to 12. The trial deliberately tested only the timing of the recommendation, not a package of added interventions, to isolate the effect of starting earlier.
Starting earlier appeared to have practical advantages. The age-9 well-child visit typically involves fewer vaccines than the 11- or 12-year visit, and clinicians can frame HPV vaccination as cancer prevention rather than a discussion tied to sexual health. Reassuringly, earlier HPV vaccination did not reduce rates of other recommended vaccines or later well-child visits, and O'Leary noted that available data show no waning of protection over time. Parental hesitancy was similar between the groups, with the main pushback in the early-start group coming from parents who did not expect a shot at the visit.