TOKYO: Japan on Monday reported its first cases of a novel coronavirus variant in which infection routes could not be traced.

The cases involved three people in Shizuoka Prefecture, central Japan, who tested positive for the same variant currently spreading in Britain, the health ministry said.

All three have no record of traveling abroad. Takaji Wakita, director-general of the National Institute of Infectious Diseases, told a news conference that domestic infection of the variant may have happened.

The three, two women in her 20s and 40s and a man in his 60s, developed symptoms early this month and are undergoing care at home and have not had interactions with the public at large. The woman in her 40s may have been infected with the variant via the other woman.

The infection of the two women was found through tracing of a person who is suspected of being infected with a new variant but has no record of traveling to Britain. The infection of the man came to light through a genome analysis on coronavirus patients.

The ministry also said that a man in his 20s in Tokyo, who entered Japan from Britain on Dec. 31, tested positive for a coronavirus variant. Japan has thus confirmed 45 variant cases.

JIJI Press