Human papillomavirus (HPV) causes 35,900 US cancer cases per year, 4,000 deaths, and $4 billion in can In this study, the investigators will conduct a 3-arm clustered randomized controlled trial (RCT) in an estimated 72 practices from up to 8 health systems to evaluate the effectiveness and cost effectiveness of two potentially scalable implementation strategies (based on prior work) to increase the initiation of HPV vaccine against a usual care (control) arm. The intervention arms are 1) online provider communication training only ("STOP-HPV-Online" and 2) online provider communication training plus a Learning Collaborative, with performance feedback, attended by practice leads ("STOP-HPV-LC).

cer-related costs. It is recommended at ages 11-12 years routinely but can be given starting at ages 9-10 years. Despite having an effective vaccine, HPV vaccine initiation/completion rates in the U.S. were only at 76.8%/61.4% respectively in 2023 among 13-17 year olds; these rates are lower than the other recommended adolescent vaccines. Two key barriers are 1) suboptimal clinician communication to address parental concerns and 2) ineffective office systems causing missed vaccine opportunities.

In prior work, the investigators have tested two implementation strategies/interventions that were effective, but which were deployed by the research team. The first is provider communication training ("STOP-HPV-Online"), delivered by the research team, in a cluster RCT in 48 pediatric practices from a research network (6.8% improvement in initiation). The other is a quality improvement, pre-post study, that included both provider communication training, as well as a Learning Collaborative (LC) for practice leads (8% increase in initiation).

A major challenge in implementation science and spreading practice-based strategies is to move from research teams deploying implementation strategies (intervention) to health systems deploying them. In this study, the investigators will compare the effectiveness and cost-effectiveness of the two implementation strategies (interventions) using a 3-arm clustered RCT: 1) STOP-HPV-Online vs 2) STOP-HPV-LC vs 3) usual care. The study team will randomize an estimated 72 practices (from up to 8 health systems) to the 1) STOP-HPV-Online arm, 2) the STOP-HPV-LC arm or 3) the control arm, assess fidelity to the intervention and conduct the evaluation. A collaborating organization, AMGA (the American Medical Group Association), will facilitate training of the health system personnel, as needed; however, the health systems will deploy each intervention. The primary outcome measure is the initiation rate among 9-<13 year olds with a well-child care visit during the 12 month intervention period (with inclusion starting at the time of a well child care visit during the intervention period). A secondary outcome measure will be the initiation rate among 13-17 year olds with a well child care visit during the intervention period (with inclusion starting at the time of a well child care visit during the intervention period. For both measures, inclusion criteria will be: 1) presenting to a participating practice, 2) age eligible at the visit and 3) no prior vaccine at the time of the visit.

Inclusion Criteria:

• Patient of participating practice
• Well child care visit during the 12-month intervention period
• No prior dose of HPV vaccine at the time of the well child care visit
• Age-eligible

Exclusion Criteria:

• Prior dose of HPV vaccine