Differences between the first and second waves of the new coronavirus (COVID-19) in Japan

There is a report of investigating the difference between the first wave and the second wave of the new coronavirus in Japan.
https://www.journalofinfection.com/article/S0163-4453(20)30693-9/fulltext

The first wave peaked in April 2020, and the second wave peaked in August of the same year. In the second wave, it is said that the mutation of D614G has increased infectivity, but it is clearly shown that the severity rate is down. However, in the second wave, there are more young people infected than in the first wave, which may be causing the severity rate to be lowered.

 

 

 

 

It is said that it is already in the third wave now, and what kind of change is happening to the infectivity and the severity rate is paid attention further.