Abstract
IMPORTANCE: There is limited evidence on whether COVID-19 vaccine incentive lotteries help to increase vaccine uptake. OBJECTIVE: To estimate whether and to what extent statewide implementation of lottery programs is associated with COVID-19 vaccine uptake. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study used data from 403 714 adults who answered the question, "have you received a COVID-19 vaccine?" on the Household Pulse Survey (HPS) and state-level daily vaccination rates for 11 states implementing a vaccine lottery program (ie, treated states) and 28 states with no such program (ie, control states). A difference-in-difference (DiD) analysis used responses to the HPS question and compared changes in vaccine uptake between treated and control states. The augmented synthetic control (ASC) analysis compared state-level daily new vaccination rates in treated states with their synthetic versions constructed from a donor pool of control states. Data were analyzed from March 17 to July 5, 2021. EXPOSURES: Announcement of the vaccine lottery programs and states implementing such programs. MAIN OUTCOMES AND MEASURES: The outcome variable in the DiD analysis was the binary indicator of self-reported vaccination status. In the ASC analysis, it was the state-level daily new first vaccine dose administered per 100 000 people (logarithm scale). RESULTS: A total of 403 714 individuals (mean [SD] age, 52.7 [15.7] years; 239 563 [weighted percentage, 51.6%] women; 31 746 [weighted percentage, 11.9%] Black; 39 709 [weighted percentage, 18.2%] Hispanic; 334 034 [weighted percentage, 76.4%] White) responded to the question in HPS regarding vaccination status. Overall, 80 949 respondents (weighted percentage, 28.1%) in the HPS were unvaccinated. A pooled analysis from both methods indicated that the lottery programs were associated with increased vaccinations. The ASC analysis revealed that lottery programs were associated with an increase of 0.208 log points (95% CI, 0.004-0.412 log points), implying an average 23.12% increment in the new daily vaccination rate. In state-specific analyses, both methods suggested that the vaccine lottery programs were helpful in Ohio (0.09 log points; P < .001), Maryland (0.26 log points; P < .001), Oregon (0.15 log points; P = .002), and Washington (0.37 log points; P < .001) but not in Arkansas, Kentucky, and West Virginia. The ASC analysis found that lottery programs were positively associated with vaccinations in New Mexico (0.32 log points; P < .001) and New York (0.33 log points; P = .001). CONCLUSIONS AND RELEVANCE: The findings of this study suggest that lottery programs may be associated with decreased COVID-19 vaccine hesitancy, but that success might differ across states. The findings could also be useful in the ongoing debate on persuading US residents who are not yet vaccinated.