Decreased Case Fatality Rate of COVID‐19 in the Second Wave: A study in 53 countries or regions

Abstract

The raw case fatality rate (CFR, reported number of COVID‐19 deaths divided by the number of cases) is an important indicator to quantify the severity or treatment efficacy. In many countries, the pandemic had two waves to date. To our knowledge, no studies have compared the CFR between the two waves. In this work, we report that of 53 countries or regions with the highest death tolls, 43 had lower CFR estimates in the on‐going second wave than in the first wave . We discussed the possible reasons. Also, we compared the two‐wave pattern of COVID‐19 with those of influenza. Influenza activities in the pre‐pandemic era provided an indicator for seasonality of climate in a country. The sharp drop in 2020 influenza activity is an indicator of the effects of social distancing.