Japan Times: COVID-19 delta strain self-destructed and Japan's incidence rate decreased 
COVID-19 incidence decreased in Japan since then how the delta strain of the virus self-destructed. This version was made by a professor at the National Institute of Genetics Ituro Inoue in a conversation with the Japan Times.
He suggested that this subspecies disappeared due to constant mutations, which “broke” the delta strain of coronavirus.
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In addition, the incidence in Japan could have decreased due to high vaccination rates and compliance with measures to protect against infection.
The country broke records for daily incidence for three months: the number of cases reached 26 thousand. To date, this figure barely reaches 200 cases.
Russian virologist, doctor of medical sciences, professor of the Department of Infectology and Virology of the Institute of Professional Education of the Sechenov University Anatoly Altstein also estimated the likelihood of self-destruction of the delta strain of coronavirus. In his opinion, now self-destruction of the delta strain of coronavirus is unlikely, but there is a rational grain in the theory of Japanese scientists.