COVID-19 Booster Vaccination Bellwethers: Factors Predictive of Older Adults' Adoption of the Second Booster COVID-19 Vaccine in Israel: A Longitudinal Study.

Israel became the first country to offer the second COVID-19 booster vaccination. The study tested for the first time, the predictive role of booster-related sense of control (SOC_B), trust and vaccination hesitancy (VH) on adoption of the second-booster among older adults, 7 months later. Four hundred Israelis (≥60 years-old), eligible for the first booster, responded online, two weeks into the first booster campaign. They completed demographics, self-reports, and first booster vaccination status (early-adopters or not). Second booster vaccination status was collected for 280 eligible responders: early- and late-adopters, vaccinated four and 75 days into the second booster campaign, respectively, versus non-adopters. Multinomial logistic regression was conducted with pseudo R 2 = .385. Higher SOC_B, and first booster early-adoption were predictive of second booster early-vs.-non-adoption, 1.934 [1.148-3.257], 4.861 [1.847-12.791]; and late-vs.-non-adoption, 2.031 [1.294-3.188], 2.092 [0.979-4.472]. Higher trust was only predictive of late-vs.-non-adoption (1.981 [1.03-3.81]), whereas VH was non-predictive. We suggest that older-adult bellwethers, second booster early-adopters, could be predicted by higher SOC_B, and first booster early-adoption, 7 months earlier.