LAUSR

BACKGROUND AND OBJECTIVES Among children requiring 2 influenza doses in a given season, second dose receipt nearly halves the odds of influenza. Nationally, many children do not receive both needed doses. This study sought to compare the effectiveness of text message reminders with embedded interactive educational information versus usual care on receipt and timeliness of the second dose of influenza vaccine. METHODS This trial took place over the 2017 to 2018 and 2018 to 2019 influenza seasons among 50 pediatric primary care offices across 24 states primarily from the American Academy of Pediatrics' Pediatric Research in Office Settings practice-based research network. Caregiver-child dyads of children 6 months to 8 years in need of a second influenza vaccination that season were individually randomized 1:1 into intervention versus usual care, stratified by age and language within each practice. Intervention caregivers received automated, personalized text messages, including educational information. Second dose receipt by April 30 (season end) and by day 42 (2 weeks after second dose due date) were assessed using Mantel Haenszel methods by practice and language. Analyses were intention to treat. RESULTS Among 2086 dyads enrolled, most children were 6 to 23 months and half publicly insured. Intervention children were more likely to receive a second dose by season end (83.8% versus 80.9%; adjusted risk difference (ARD) 3.8%; 95% confidence interval [0.1 to 7.5]) and day 42 (62.4% versus 55.7%; ARD 8.3% [3.6 to 13.0]). CONCLUSIONS In this large-scale trial of primary care pediatric practices across the United States, text message reminders were effective in promoting increased and timelier second dose influenza vaccine receipt.