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Published on: November 10, 2023
Geographical variation in case fatality rate and doubling time during the COVID-19 pandemic
A Mazumder1, M Arora1, M S Sra1
1All India Institute of Medical Sciences (AIIMS), New Delhi, India.
Insights
This study introduces a cumulative case fatality rate (cCFR) method for more stable epidemic analysis. It reveals significant international variations in COVID-19 outcomes and epidemic control.
Area of Science:
- Epidemiology
- Infectious Disease Dynamics
- Public Health
Background:
- Case fatality rate (CFR) and doubling time are critical epidemic metrics.
- COVID-19 exhibits significant international variability in CFR and doubling time.
- Traditional CFR calculations are inaccurate early in an epidemic due to unknown outcomes.
Purpose of the Study:
- To introduce a cumulative case fatality rate (cCFR) for temporal stability.
- To estimate daily average doubling time for COVID-19.
- To analyze international variations in CFR and epidemic control.
Main Methods:
- Calculated cumulative CFR using only patients with known outcomes.
- Estimated daily average doubling time.
- Compared cCFR and doubling times across different countries.
Main Results:
- The cCFR method provides temporally stable fatality rates.
- Countries like the US, France, Turkey, and China initially had high cCFR.
- Germany, China, and South Korea showed low cCFR by April 22.
- China and South Korea demonstrated effective epidemic control with high doubling times.
- Russia's doubling time remained under 10 days.
Conclusions:
- The cCFR method offers a more reliable measure of epidemic fatality.
- Improved outcomes and wider testing strategies influence cCFR stability.
- Effective epidemic control is linked to high doubling times and reduced cCFR.
Abstract:
Case fatality rate (CFR) and doubling time are important characteristics of any epidemic. For coronavirus disease 2019 (COVID-19), wide variations in the CFR and doubling time have been noted among various countries. Early in the epidemic, CFR calculations involving all patients as denominator do not account for the hospitalised patients who are ill and will die in the future. Hence, we calculated cumulative CFR (cCFR) using only patients whose final clinical outcomes were known at a certain time point. We also estimated the daily average doubling time. Calculating CFR using this method leads to temporal stability in the fatality rates, the cCFR stabilises at different values for different countries. The possible reasons for this are an improved outcome rate by the end of the epidemic and a wider testing strategy. The United States, France, Turkey and China had high cCFR at the start due to low outcome rate. By 22 April, Germany, China and South Korea had a low cCFR. China and South Korea controlled the epidemic and achieved high doubling times. The doubling time in Russia did not cross 10 days during the study period.
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