Introduction Previous studies have identified an increase in the percent of the population dying from firearms during vs. before the COVID-19 pandemic. Such increases have been attributed to a rise in mental health disorders due to medical and financial fear, social isolation, and social unrest. This paper describes in more-depth such changes in the three most-populous counties in the United States: Cook (Chicago), Los Angeles, and New York.

Methods Data was collected from the publicly-available, anonymized/de-identified, and aggregated CDC WONDER database. A chi square test compared rates of firearm deaths by county in 2019 and 2021, with comparisons being made between counties within one year (eg, Cook vs. Los Angeles in 2019) and within a county between years (eg, Cook in 2019 vs. Cook in 2021). We also performed a chi square test to compare changes in the rates of percent of firearms deaths from 2019 to 2021 between the counties.

Results In 2019 and 2021, there were statistically-significant differences in the percent of the population dying from firearms between Cook, Los Angeles, and New York counties (both years: p <0.0001) (Tables 1 and 2). In each county, there was also a statistically-significant increase between 2019 and 2021 in the percentage of population dying from firearms (p <0.0001). (Table 3) However, the rate of increase was not different between the three counties (p = 0.16). That is, the increase in percent of population dying from firearms between 2019 and 2021 in Cook County was not different from that increase in Los Angeles or New York counties.

Discussion Rates of death from firearms increased between 2019 and 2021 in the three largest counties in the United States: Cook, Los Angeles, and New York. The current study validates the findings of prior studies. However, we found the rate of increase was not statistically-significant between the three counties. Numerous causes may underlie the increase, including changes in mental health related to pandemic stressors (physical isolation, unemployment, and actual or fear of poverty1) or difficulty accessing mental health services.

The authors have declared no competing interest.

The study did not receive any funding.

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The study used only openly available human data that were originally located at:https://www.cdc.gov/nndss/infectious-disease/weekly-and-annual-disease-data-tables.html

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