OBJECTIVES

In 2014, New York City initiated a childcare influenza vaccine requirement to increase influenza vaccination rates among children aged 6-59 months attending city-regulated childcare, including prekindergarten. We evaluated the requirement's effect on vaccination rates in childcare-aged children in New York City.

METHODS

We examined influenza vaccination rates in children aged 6-59 months and by age groups of 1, 2, 3, and 4 years for 8 influenza seasons (2012-2013 through 2019-2020), representing 2 seasons before the requirement, 2 seasons during the requirement, 2 seasons after its suspension, and 2 seasons after its reinstatement. We also assessed rates in a comparison group of children aged 5-8 years. We performed a difference-in-differences analysis to compare rate differences in age groups when the requirement was and was not in effect. We considered  < .05 as significant based on the Wald χ test.

RESULTS

Influenza vaccination rates among children aged 6-59 months increased 3.7 percentage points (from 47.7% to 51.4%) by the requirement's second year and declined 6.7 percentage points to 44.7% after suspension. After reinstatement, rates increased 10.7 percentage points to 55.4%. Rate changes were most pronounced among 4-year-olds, increasing 12.7 percentage points (from 45.3% to 58.0%) by the requirement's second year, declining 14.1 percentage points to 43.9% after suspension, and increasing 22.2 percentage points to 66.1% after reinstatement. In the comparison group, rates increased 4.9 percentage points (from 36.5% to 41.4%) after reinstatement. Rates increased significantly among 4-year-olds before versus at the initial requirement and decreased significantly after suspension. After reinstatement, rates increased significantly among all groups except 1-year-olds.

CONCLUSION

The New York City influenza vaccine requirement improved influenza vaccination rates among preschool-aged children, adding to the evidence base showing that vaccine requirements raise vaccination rates.