Among the new coronaviruses, infection with a virus called "XE", which is a combination of multiple types of Omicron strains, was confirmed for the first time in domestic quarantine.
According to the Ministry of Health, Labor and Welfare, the infection was confirmed in a woman in her thirties who arrived at Narita Airport from the United States on March 26.
She was tested positive for the new coronavirus at the airport quarantine station, and her genetic analysis at the National Institute of Infectious Diseases confirmed her to be "XE."
XE has been reported in the United Kingdom and elsewhere, but this is the first time that infection has been confirmed in Japan.
"XE" is a combination of "BA.1", an Omicron strain that spread in "6th wave", and "BA.2", which is said to be more infectious. It is estimated that the spread of infection is 12.6% faster than "BA.2".
Takaji Wakita, chairman of the Ministry of Health, Labor and Welfare's expert meeting, said last week, "The infection is not widespread in the UK, and the relationship with severity is not well understood."