United States Forces Korea said Tuesday that the widow of one of its service members tested positive for COVID-19 after she had visited a military base in Daegu.

The patient, 61, is the first individual linked to USFK to test positive for the virus. Two weeks ago, she visited twice the post exchange at Camp Walker, one of three American installations in Daegu, where infections recently skyrocketed because of mass gatherings at a Shincheonji church.

USFK raised the risk level to “high” from “moderate” and began conducting temperature checks and screening questionnaires at the entrances to its bases. Nonessential meetings and duty travel were suspended, and people on bases were asked to stay put. Visitors were not allowed.

The US military had already banned nonessential travel and visits to the Daegu bases and shut down schools there. Meanwhile, the Korean military reported 18 infections, with 9,230 under quarantine as of Tuesday evening. The military expanded the quarantine as some patients showed few or no symptoms.

By Choi Si-young (siyoungchoi@heraldcorp.com)