OBJECTIVES: The objective of this study was to describe changes in the volume and types of emergency medical services (EMS) calls for children during the COVID-19 pandemic and after availability of the COVID-19 vaccine ("reopening period"). METHODS: A retrospective cross-sectional study of EMS 9-1-1 responses to children under 18 years for all causes over a 4-year period (2019-2022) reported in the National Emergency Medical Services Information System (NEMSIS) dataset. Data was stratified into three periods, Pre-pandemic, Pandemic and Reopening. We used generalized linear models to estimate the effect of the pandemic and reopening on daily call volume trends, on-scene mortality and scene disposition, correcting for seasonality and baseline effects. We performed subgroup analyses based on geographic region and diagnosis (trauma, respiratory, mental health, seizure, diabetes). RESULTS: A total of 4,612,505 pediatric EMS 9-1-1 responses were included. Call volume for EMS showed an increasing pre-pandemic trend (+25.9%/year) followed by an acute drop in volume (-28.9%) and decreased trend (-13%/year) during the pandemic period and a rebound (+17.5%) during the reopening period that was generally conserved across all regions. Subgroup analysis by diagnosis showed similar trends among a wide variety of illnesses. There were increased odds of on-scene death for calls for traumatic (OR 1.77) and respiratory (OR 2.00) illnesses, with partial reversal in the respiratory group (OR 0.66) during the reopening period. During the pandemic, children were less likely to be transported (OR 0.70) and more likely to be non-transported (OR 1.30) and refuse care (OR 1.32), with partial reversal of these trends during the reopening period. CONCLUSIONS: The pre-pandemic increase in EMS call volume was disrupted by an acute pandemic-related decline followed by a rebound during reopening. During the pandemic, children were more likely to present with more severe manifestations of disease processes, particularly increased on-scene death for trauma and respiratory illness, and less likely to be transported-with only partial reversal of trends in reopening.