SEOUL - A "superspreader" is suspected of giving the new coronavirus to 15 other people in South Korea as health authorities reported 20 new infection cases on Wednesday to bring the nation's total to 51.

The Korea Centers for Disease Control and Prevention said in a statement that the woman had contact with 14 of them at church and the other one at a hospital.

She has already been released from a hospital in Daegu, a city about 240 kilometers southeast of Seoul, where she had been treated between Feb. 7 and 17.

Director Jung Eun Kyeong said at a regular briefing that tests will be conducted on the entire congregation at the church as the woman is believed to have had contact with many people there.

Altogether she had contact with 166 others, 128 of them at the hospital. All of them were being self-quarantined as of Wednesday, according to the health authorities.

How the woman got the virus remains unclear, however, as she has no recent history of traveling abroad or having contact with others who had already tested positive for the virus.

Upon her visit to the hospital, she refused to be tested at first, but then her pneumonia became more serious, the authorities said.