The government said Wednesday that it plans to carry out a full-scale investigation into a church in the southern city of Daegu, which has emerged as the largest cluster of the new coronavirus disease with 14 cases.

South Korea reported 20 new cases of COVID-19 the same day, increasing the total to 51.

According to the Korean Centers for Disease Control and Prevention, of the new cases, 18 were in Daegu, the third-largest city in the country, and nearby North Gyeongsang Province. Fifteen are believed to be linked to a 61-year-old woman who became the country’s 31st patient Tuesday.

She attends the Sincheonji Church of Jesus, a non-mainstream religious group, 14 of whose members tested positive Wednesday. A person from a hospital that the 31st patient visited was also confirmed to have contracted the virus.

The new cases raised alarm as they represent the first group of infections that appear to have stemmed from a single “super-spreading event.”

KCDC Director Jung Eun-kyeong said health authorities are mapping out plans to conduct screening and diagnostic tests on the church’s members.

She admitted that super spreading had taken place at the church but took a cautious approach on labeling the 31st patient a “super-spreader.”

“South Korea is facing a situation similar to that in Singapore and Japan, which have seen clusters of virus cases in churches,” Jung said.

“We still need to see who has infected whom in order to confirm whether she is a super-spreader,” Jung said in a press conference.

The government is not considering imposing a lockdown on Daegu and has no plans to raise its infectious disease alert level. Korea is currently at the third-highest readiness level in the four-tier system.

The country’s 31st patient was hospitalized through Monday after a car accident Feb. 6. She stayed alone in a four-bed ward at a hospital in Daegu. During the hospitalization period she visited the church twice, including a service this past Sunday that 460 people attended.

The KCDC said the 31st patient had refused to take the COVID-19 kit test at a Feb. 8 visit to the hospital despite doctors’ recommendation.

Wednesday’s newly diagnosed patients include a 10-year-old girl in Suwon, the country’s first juvenile COVID-19 patient. A man in Seoul was also found to have been infected via an unclear transmission route.

By Park Han-na (hnpark@heraldcorp.com)