The Influence of SARS-CoV-2 Variants on National Case-Fatality Rates: Correlation and Validation Study

Area of Science:

• Epidemiology
• Public Health
• Virology

Background:

• The emergence of SARS-CoV-2 variants of concern (VoCs) like Alpha, Gamma, and Delta in 2021 led to increased transmissibility and virulence.
• The Delta variant became dominant globally in the latter half of 2021, significantly impacting infection dynamics.

Purpose of the Study:

• To analyze how SARS-CoV-2 VoCs influence COVID-19 case-fatality rates (CFRs) across diverse global regions.
• To investigate the correlation between specific comorbidities and mortality risk during VoC-dominated periods.
• To assess the impact of vaccination rates on reducing mortality risk.

Main Methods:

• Introduction of a proxy CFR (pCFR) metric to track temporal infection dynamics and enable cross-country comparisons.
• Utilized economic, demographic, epidemiological, and medical data from global sources for analysis.
• Computed average and daily COVID-19 CFRs and their correlations with potential cofactors for 2021.

Main Results:

• Chronic kidney disease exhibited the strongest correlation with COVID-19 fatality (0.36).
• Asthma (0.26) and coronary heart disease (0.26) also showed significant positive correlations with mortality.
• The pCFR proved effective in tracking infection waves driven by different VoCs within countries.

Conclusions:

• The influence of social, economic, and medical factors on CFRs due to VoCs is qualitatively similar but strengthened compared to the wild strain.
• Significant regional variations in cofactor influence persist, highlighting the impact of economics, healthcare policies, and cultural practices.
• While VoC spread patterns were evident, limited evidence suggests widespread transmission of Lambda and Mu variants beyond South America.