A detailed analysis of the genetic information of the new coronavirus Omicron strain detected in Japan by the National Institute of Infectious Diseases revealed that it may have entered the country by at least four routes so far.

The National Institute of Infectious Diseases analyzed 2650 cases of the new coronavirus Omicron strain, for which detailed genetic information was reported in Japan by the 17th of last month.

As a result, it was found that there are at least four groups of domestic Omicron strains, each of which may have come from overseas by different routes.

One of these is the mainstream virus that is prevalent in the country, and is the same or similar strain of virus that is often detected in the United States.

In addition, the virus that spread nationwide such as Kanto after being confirmed in the Kyushu region is the same as or close to the strain detected in the United States and the United Kingdom, and the virus that spread in the Kanto region and Tohoku region is detected in Europe and Asia. It means that it is a kind close to the system with many viruses.

On the other hand, the virus that was widely detected in the Kansai region from the end of December last year has not spread since then, and it is thought that it has converged due to cluster measures.

According to the National Institute of Infectious Diseases, "By analyzing the results of analysis of genetic information together with epidemiological studies, it will be useful to deepen the understanding of the infection route and the mechanism of infection spread of Omicron strains."