School Mandate and Influenza Vaccine Uptake Among Prekindergartners in New York City, 2012-2019.

New York City (NYC) introduced a universal prekindergarten program in 2014 that mandated influenza vaccination for enrollment. We conducted a difference-in-difference-in-differences study to evaluate the program using 2012 to 2019 MarketScan claims data. After the introduction of the program, influenza vaccine uptake among four-year-old children in NYC during the subsequent seasons increased by 6.3 to 9.8 percentage points compared with the rest of New York State. (Am J Public Health. Published online ahead of print March 24, 2022: e1-e5. https://doi.org/10.2105/AJPH.2022.306765).