RÉSUMÉ
OBJECTIVE: To evaluate the effect of different modalities of centralized reminder/recall (autodialer, text, mailed reminders) on increasing childhood influenza vaccination. STUDY DESIGN: Two simultaneous randomized clinical trials conducted from October 2017 to April 1, 2018, in New York State and Colorado. There were 61 931 children in New York (136 practices) and 23 845 children in Colorado (42 practices) who were randomized to different centralized reminder/recall modalities-4 arms in New York (autodialer, text, mailed, and no reminder control) and 3 arms in Colorado (autodialer, mailed, and no reminder control). The message content was similar across modalities. Up to 3 reminders were sent for intervention arms. The main outcome measure was receipt of ≥1 influenza vaccine. RESULTS: In New York, compared with the control arm (26.6%), postintervention influenza vaccination rates in the autodialer arm (28.0%) were 1.4 percentage points higher (adjusted risk ratio, 1.06; 95% CI, 1.02-1.10), but the rates for text (27.6%) and mail (26.8%) arms were not different from controls. In Colorado, compared with the control arm (29.9%), postintervention influenza vaccination rates for the autodialer (32.9%) and mail (31.5%) arms were 3.0 percentage points (adjusted risk ratio, 1.08; 95% CI, 1.03-1.12) and 1.6 percentage points (adjusted risk ratio, 1.06; 95% CI, 1.02-1.10) higher, respectively. Compared with the control arm, the incremental cost per additional vaccine delivered was $20 (New York) and $16 (Colorado) for autodialer messages. CONCLUSIONS: Centralized reminder/recall for childhood influenza vaccine was most effective via autodialer, less effective via mail, and not effective via text messages. The impact of each modality was modest. Compared with no reminders, the incremental cost per additional vaccine delivered was also modest for autodialer messages. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03294473 and NCT03246100.