Effect of Targeted Behavioral Science Messages on COVID-19 Vaccination Registration Among Employees of a Large Health System

The first opportunities to field test interventions to increase COVID-19 vaccination were among health care workers (HCWs), who were among the first to be offered COVID-19 vaccines. After 1 large Pennsylvania health system sent 36 vaccine-related mass emails to employees over 5 weeks (eAppendix in Supplement 1), 9723 of 23 700 HCWs (41%) had still not scheduled their vaccination. We sought to determine whether individually addressed emails designed with behaviorally informed features1,2,3,4,5 could increase vaccination registration compared with a delayed control group.