South Korea's new coronavirus cases slowed Thursday, but health authorities are still fretting over further community spread tied to entertainment facilities and a hospital.

The 12 new cases detected Wednesday raised the total caseload to 11,122, according to the Korea Centers for Disease Control and Prevention (KCDC). Of them, 10 were local infections.

The country reported 32 COVID-19 cases Wednesday, marking the largest uptick in nine days, as it reeled from a steady rise in nightclub-related cases in Itaewon, a popular nightlife area in the capital.

South Korea has successfully flattened the virus curve with massive and swift testing, but sporadic cluster infections continue to complicate public health authorities' quarantine efforts.

Cases tied to clubs in Itaewon have not evolved into explosive infections but have continued to increase steadily. The number of virus cases linked to the Itaewon cluster reached 206 as of noon, with 10 new patients added over the past 24 hours.

Itaewon emerged as a hotbed for infections after a 29-year-old man tested positive for COVID-19 on May 6 following visits to clubs in the district in early May.

The country continued to report secondary and tertiary transmissions linked to the Itaewon outbreak.

To stem further community spread, the city government in Incheon, west of Seoul, ordered some 2,400 karaoke facilities in the city not to host customers for two weeks, virtually suspending businesses at such places.

Incheon reported 40 cases tied to Itaewon clubs as of noon, trailing 101 cases in Seoul and 45 in Gyeonggi Province that surrounds the capital.

The government said it is considering implementing the same administrative order nationwide as more infections tied to karaoke facilities have been reported.

"The Itaewon outbreak has not led to massive virus spread, but related infections have been reported consistently. That's why health authorities cannot loosen their guard against community spread," Yoon Tae-ho, a senior health official, said in a briefing.

Health authorities are also on alert over looming infections at a hospital in southern Seoul.

Since four nurses working at Samsung Medical Center, one of the country's five major general hospitals, were confirmed to be infected, health authorities have conducted tests on 1,418 people.

No additional infections traced to the hospital were reported, but health authorities are conducting an epidemiological survey on two virus patients who came in contact with one of the infected nurses.

The KCDC said more related cases are likely to spring up, as transmission routes are still unknown.

It said Wednesday the nurses may have been infected at shared spaces, such as changing rooms, in the hospital or through patients undergoing surgery.

The agency said it has yet to find a link between their cases and those tied to nightclubs.

Health authorities remain on alert over further community spread, as more schools are set to reopen after high school seniors began to return to schools Wednesday.

Incheon, west of Seoul, and Anseong, south of the capital, ordered third graders at 75 high schools to return home on Wednesday. Two high school students tested positive for COVID-19 in Incheon in cases related to the Itaewon cluster.

Earlier in the day, a high school in the southeastern city of Daegu, once the epicenter of the virus outbreak here, was closed as a third grader who used a school dormitory was infected.

Seoul's southwestern Yangcheon Ward is considering delaying the reopening of at least three elementary schools set for May 27 due to a church-related case in the district.

The country, meanwhile, added two imported cases and reported one additional death, raising the total death toll to 264. The fatality rate was 2.37 percent.

The total number of people released from quarantine after full recoveries stood at 10,135, up 69 from the previous day.

Since Jan. 3, the country, with a population of more than 50 million, has carried out 788,684 tests, including 12,251 the previous day. (Yonhap)