Helping people accurately understand their risk of dying or surviving may support public health campaigns years later. A new strategy for improving health behavior is supported by a randomized controlled trial from the longrunning Malawi Longitudinal Study of Families and Health (MLSFH) that showed that a 2017 intervention to correct misconceptions about mortality risk was linked to higher COVID-19 vaccination rates five years later. Vaccination was 7.8 percentage points higher in the intervention than the control group. Effects spread to families of intervention participants, whose siblings had higher vaccination rates than the control group.