The country reported 100 new cases of the novel coronavirus as of 4 p.m. on Friday, bringing the total number to 204, the Korea Center for Disease Control and Prevention (KCDC) said.
But a few more virus cases, not officially counted by the health authorities, were also reported in many cities.
A woman in her mid-50s, who was confirmed to be infected with the virus, died at a hospital in the southeastern city of Busan at around 6 p.m., hospital officials said.
She had been bedridden with chronic pneumonia at Daenam Hospital in Cheongdo County and was transferred to Busan National University Hospital after she tested positive for the virus earlier Friday.
Daenam is where the nation's first COVID-19 fatality occurred. On Thursday KCDC said a 63-year-old man, who died of pneumonia there on Wednesday, posthumously tested positive for the virus.
The country's most new infections have been traced to church services in the southeastern city of Daegu.
Daegu, where the 2.5 million inhabitants have been asked to stay indoors, and neighboring Cheongdo were designated as a "special management zone" earlier in the day. The nation's capital, Seoul, banned demonstrations in downtown areas.
Of the 100 new cases, 86 are in Daegu, 300 kilometers southeast of Seoul, and neighboring North Gyeongsang Province. Another seven were reported in Seoul, the KCDC said.
The health authorities vowed to make more containment efforts as the potentially fatal illness spreads fast across the country.
Health and Welfare Minister Park Neung-hoo told reporters that the health authorities will allow hospitals to separate respiratory patients from others in an effort to prevent human-to-human transmissions at hospitals.
Health authorities will also check all pneumonia patients in Daegu hospitals, Park said.
Still, the authorities have kept the virus alert at the third-highest, or "orange," level, but the virus response will be carried out with an urgency appropriate to the "red" level, Park said.
The spike of infections in Daegu and several cases in Seoul, where routes of infections are not immediately traceable, have prompted health officials to declare that COVID-19 has begun spreading locally.
The KCDC said eight new cases were reported in South Gyeongsang Province. In a sign that the virus may broadly spread nationwide, other provinces, including Jeju, Chungcheong and North Jeolla, reported cases. Gyeonggi Province also reported more new cases.
There were first two new virus cases reported in Busan, the country's second-largest city with a population of 3.4 million. The city has been regarded as relatively free of the virus outbreak since the country reported the first COVID-19 on Jan. 20.
Of the two, a 19-year-old man tested positive for the virus, and had not been abroad recently.
But Busan City officials said his father was released last week after two-week quarantine at a state-designated facility after being airlifted from Wuhan, the epicenter of the virus outbreak.
Of the 100 new cases, 85 are linked to the Shincheonji Church of Jesus in Daegu, where the 31st patient, the country's probable "super spreader," attended worship services, the KCDC said.
A 61-year-old South Korean woman, who tested positive for the virus earlier this week, attended worship services at the church on Feb. 9 and this past Sunday.
The total accumulated number of confirmed cases in Daegu and its neighboring North Gyeongsang Province stood at 153, with the number of cases linked to the Daegu church coming to 128.
"Currently, the COVID-19 situation at home is that the scope of mass outbreak via a single exposure is relatively big," KCDC Director Jung Eun-kyeong said.
Health authorities are investigating how the Daegu church was infected by the virus, Jung said.
The religious organization has branches in China and other nations, Jung said, adding that the investigation included whether the church members visited China's Hubei province, the epicenter of the virus.
Most virus-infected patients are stable, but about seven patients with underlying illness are in relatively critical conditions, Jung said.
The number of confirmed cases at the Daenam Hospital in Cheongdo, near Daegu, stood at 17, including five nurses, the KCDC said.
In a separate statement, the KCDC said the man with chronic pneumonia had been hospitalized for a long time, and he died as the illness worsened.
A group of health experts suspected the man died from the virus, but they expressed opinions that his death might have been also caused by other factors, the KCDC said.
The 31st patient also visited Cheongdo before testing positive for the virus, but she did not visit the Daenam Hospital, the KCDC said, adding that a larger probe is needed to identify how the 16 people at the hospital, including five medical staff members, were infected by the virus.
South Korea is set to release one more fully recovered novel coronavirus patient from a hospital later in the day, the KCDC said. So far, a total of 16 patients have been discharged.
The number of people being checked for the virus and under quarantine came to 3,180, up from 2,707 a day earlier, the KCDC said.
South Korea has screened 16,400 people for COVID-19 since Jan. 3, with 13,016 testing negative and 17 patients having been discharged from quarantine after making full recoveries.
The World Health Organization (WHO) said that despite the spike in infections in South Korea, the situation is manageable.
In Geneva, WHO Director-General Tedros Adhanom Ghebreyesus told reporters, "I think the number of cases are really manageable. And I hope that South Korea will do everything to contain this outbreak at this early stage."
The WHO chief said South Korea's virus response "is proportionate to the public risk they have."
source: Yonhap News