The raw case fatality rate (CFR, reported number of COVID-19 deaths divided by the number of cases) is a useful indicator to quantify the severity or treatment efficacy in a locality. In many countries, the pandemic showed a two-wave pattern now, namely the daily reported cases once reached a low level and now went up. To our knowledge, no study has compared the CFR for the two waves. In this work, we report that in 53 countries or regions with the highest deaths, the CFR is reduced in 43 countries or regions in the on-going second wave. We discussed the possible reasons. Also, we compare the two-wave pattern of COVID-19 with the weekly influenza positive tests. The influenza activity in pre-pandemic era provided an indicator for climate in a country, since it is well-known that influenza is driven by weather. The sharp drop in 2020 influenza activity is an indicator of the effects of social distancing.
The activity of influenza A at the end of 2019 was higher than previous two years in children younger than 6 years old in Wuhan, China. The 2019-20 seasonal influenza winter outbreak preceded the COVID-19 outbreak, with a higher and earlier peak than that of the 2017-18 and 2018-19 seasons. We speculate this could be due to the earlier CNY holiday season in 2019-20 than in previous two years. We compared these results with those of two previous studies to further discuss the possible interference between influenza and COVID-19 in young children.