EPH205 A Global Analysis of COVID-19 Infection Fatality Rate and Its Associated Factors during the Delta and Omicron Variant Periods

Abstract

This study aimed to compare COVID-19 average weekly infection fatality rate (AWIFR); to investigate factors associated with COVID-19 AWIFR over two periods of Delta and Omicron variants; and to explore the factors linked to the increase in COVID-19 AWIFR between two periods of Delta and Omicron variants. An ecological study has been conducted among 110 countries over the first twelve weeks during two periods of Delta and Omicron variant dominance using open publicly available datasets. For the countries presenting in both Delta and Omicron periods (99 countries), we calculated the increase in AWIFR. Linear mixed-effects models were used to explore factors associated with the variation of AWIFR over Delta and Omicron periods. A linear regression model was utilized to determine factors associated with the change of AWIFR between two periods of Delta and Omicron. During Delta period, our analysis indicated that the lower AWIFR were witnessed in countries with better government effectiveness index, and higher proportion of the people fully vaccinated. In contrast, higher burden of cardiovascular diseases was positively associated with AWIFR. Over Omicron period, we found that while years lived with disability (YLDs) caused by metabolism disorders, the proportion of the population aged over 65 were positively associated with poorer AWIFR, the high proportion of the population vaccinated with a booster dose was linked with the better outcome. Over two periods of Delta and Omicron, we observed the increase in government effectiveness index was associated with decrease of AWIFR; whereas higher death rates caused by diabetes and kidney and percentage of the population aged over 65 were associated with a significant increase in AWIFR. Proper policies for improvement of vaccination coverage and support vulnerable groups could substantially mitigate the burden of COVID-19, particularly in new era of pandemics.