Excess Cardiopulmonary Arrest and Mortality after COVID-19 Vaccination in King County, Washington

Introduction: Since the onset of widespread COVID-19 vaccination campaigns, there have been concerns about serious cardiovascular adverse events as a result of mass vaccination. This study aimed to estimate excess cardiopulmonary arrest mortality in King County, WA, and investigate any association with COVID-19 vaccination rates. Methods: An exploratory data analysis was performed. Comparative analyses were performed to evaluate the changes in total EMS attendances over time. Excess deaths were calculated using the 2015-2020 cardiopulmonary arrest mortality trend line. The relationship between excess cardiopulmonary arrest mortality and vaccination rates was analyzed using polynomial regression analysis. Results: Approximately 98% of the King County population received at least one dose of a COVID-19 vaccine by 2023. As of August 2nd, 2024, there have been approximately 589,247 confirmed COVID-19 cases in King County. In 2021- 2022, Total EMS attendances in King County sharply increased by 35.34% from 2020 and by 11% from pre-pandemic years. Cases of 'obvious death' upon EMS arrival increased by 19.89% in 2020, 36.57% in 2021, and 53.80% in 2022 compared to the 2017-2019 average. We found a 25.7% increase in total cardiopulmonary arrests and a 25.4% increase in cardiopulmonary arrest mortality from 2020 to 2023 in King County, WA. Excess fatal cardiopulmonary arrests were estimated to have increased by 1,236% from 2020 to 2023, rising from 11 excess deaths (95% CI: -12, 34) in 2020 to 147 excess deaths (95% CI: 123, 170) in 2023. A quadratic increase in excess cardiopulmonary arrest mortality was observed with higher COVID-19 vaccination rates. The general population of King County sharply declined by 0.94% (21,300) in 2021, deviating from the expected population size. Applying our model from these data to the entire United States yielded 49,240 excess fatal cardiopulmonary arrests from 2021-2023. Conclusions: We identified a significant ecological and temporal association between excess fatal cardiopulmonary arrests and the COVID-19 vaccination campaign. The increase in excess cardiopulmonary arrest deaths may also be attributed to COVID-19 infection and disruptions in emergency care during the pandemic. Urgent further research is needed to confirm our observations with attention to risk mitigation for incident events and improved survival with resuscitation.