Japan’s health ministry has confirmed the country’s first cases of infection with the new variant of the coronavirus that was identified in Britain.

The five people arrived between Dec. 18 and Dec. 21, before Japan stepped up border control on Friday for entrants from Britain. A man in his 60s developed fatigue, but the other four were without symptoms.

Health Minister Norihisa Tamura said the five were sent to quarantine straight from the airports.

After they tested positive for the virus, further analysis conducted at the National Institute of Infectious Diseases determined they had the British variant that is 70% more transmissible, the ministry said in a statement.

Shigeru Omi, head of a government taskforce, called for tighter border control to prevent new variants.

(AP)