First and second COVID-19 waves in Japan: A comparison of disease severity and characteristics

•Coronavirus disease has emerged as a global pandemic.•Japan has experienced two waves of the disease.•The second wave had a lower proportion of severe cases on admission. We read with interest the recent article published in your journal detailing the severity of coronavirus disease 2019 (COVID-19) in China during the first wave of the pandemic1Liu X. Zhou H. Zhou Y. Wu X. Zhao Y. Lu Y. et al.Risk factors associated with disease severity and...