Declining COVID-19 case-fatality in Georgia, USA, March 2020 to March 2021: a sign of real improvement or a broadening epidemic?

Purpose: To examine whether declines in the crude U.S. COVID-19 case fatality ratio is due to improved clinical care and/or other factors. Methods: We used multivariable logistic regression, adjusted for age and other individual-level characteristics, to examine associations between report month and mortality among confirmed and probable COVID-19 cases and hospitalized cases in Georgia reported March 2, 2020 to March 31, 2021. Results: Compared to August 2020, mortality risk among cases was lowest in November 2020 (OR =0.84; 95% CI: 0.78-0.91) and remained lower until March 2021 (OR= 0.86; 95% CI: 0.77-0.95). Among hospitalized cases, mortality risk increased in December 2020 (OR= 1.16, 95% CI: 1.07-1.27) and January 2021 (OR =1.25; 95% CI: 1.14-1.36), before declining until March 2021 (OR =0.90, 95% CI: 0.78-1.04). Conclusions: After adjusting for other factors, including the shift to a younger age distribution of cases, we observed lower mortality risk from November 2020 to March 2021 compared to August 2020 among cases. This suggests that improved clinical management may have contributed to lower mortality risk. Among hospitalized cases, mortality risk increased again in December 2020 and January 2021, but then decreased to a risk similar to that among all cases by March 2021. (C) 2022 The Authors. Published by Elsevier Inc.