Photo/Illutration Foot traffic near a Christmas tree along a pedestrian crossing in Tokyo’s Shibuya district on Dec. 17. (AP Photo)

Thirteen passengers arriving from overseas who tested positive for the Omicron variant of the novel coronavirus are now self-isolating at a medical institution, health authorities said Dec. 18.

The new arrivals, from seven nations, landed at Narita and Haneda airports between Dec. 12 and 15.

In other developments, Tokyo is experiencing a slight uptick in fresh COVID-19 cases with 28 newly confirmed ones on Dec. 18, eight more than the previous Saturday.

For the week ending Dec. 18, the daily average of new cases in the capital came to 21.6, which represented a 17.4-percent increase over the average of the previous week, metropolitan government officials said.

No related deaths were reported.

Three patients had symptoms serious enough to warrant the use of a ventilator or other equipment to breathe. The figure was unchanged from the previous day.