A population‐based reminder intervention to improve human papillomavirus vaccination rates among adolescents at routine vaccination age

•We mailed 80,894 HPV vaccine reminder letters.•The mailing was sent to parents/guardians of 11- to 13-year-olds throughout the state.•Letter recipients were more likely to start the HPV vaccine series within six months.•Similar effect sizes were seen among age and gender strata.•We used a centralized approach to efficiently reach the maximum possible population. Public health authorities have the resources to conduct efficient immunization reminder interventions to improve vaccine uptake. The objective of this initiative was to design and implement a cost-effective centralized HPV vaccine reminder using New York State Immunization Information System data as one of five prespecified activities to increase initiation and completion among 11- to 13-year-old adolescents. The New York State Department of Health sent reminder letters to the parents or guardians of eligible adolescents who were due for the first dose of HPV vaccine and observed HPV vaccine administration in the six months after each mailing. Subjects were randomized into an intervention group, mailed on May 14, 2015 and a control group, mailed on December 8, 2015. The analysis consisted of 81,558 eligible letter recipients. Letter recipients were 2 percent more likely to initiate vaccination than control subjects. Significant increases in vaccine uptake were observed for all age and gender strata. The intervention cost was $30.95 for each adolescent who initiated the HPV vaccine series. New York State Department of Health received far less public feedback, including negative feedback, about this intervention that was originally anticipated. Public health entities can effectively utilize existing resources to conduct large-scale reminder interventions targeting a jurisdiction’s entire 11- to 13-year-old population.