South Korea added 15 new cases of the coronavirus Monday as the country saw clear signs of a slowdown in nightclub-linked infections.

The new cases, detected Sunday, brought the country's total to 11,065, according to the Korea Centers for Disease Control and Prevention (KCDC). Five of them were local infections.

The country added 13 new cases a day earlier, the lowest daily increase since Itaewon, a nightlife district in Seoul, emerged as a hotbed for coronavirus infections this month.

Concerns had been rising over a second wave of infections after a group of clubgoers tested positive for COVID-19 shortly after the country decided to ease social distancing.

After a virus patient visited clubs in Itaewon in early May, the country experienced a resurgence in the number of new patients, with the daily increase reaching 35 last Monday, the highest for the month so far.

Authorities said the first patient from the Itaewon cluster is presumed to have been infected in late April, although an investigation is ongoing.

Around 5,000 people were estimated to have visited affected clubs in Itaewon between April 24 and May 6, and health authorities remain vigilant over secondary and tertiary transmission of the virus.

Health authorities said they have carried out more than 65,000 tests on people affected by the Itaewon-linked infections so far.

The number of cases linked to the cluster infection reached 170 as of Monday noon, according to the authorities. Of them, 93 cases were reported from Seoul, followed by surrounding Gyeonggi Province with 33 cases.

While South Korea believes it has brought Itaewon-linked infections under control, health authorities remain alert over what they call "hidden spreaders."

Health authorities also said a 32-year-old Vietnamese virus patient who tested positive Sunday had visited a nightclub in Bucheon, just west of Seoul, early this month. 

No secondary infections from the case were immediately reported, but health authorities urged those who visited Merit Nightclub in the city around midnight on May 9 to be tested for the virus.

South Korea reported one new death, raising the death toll to 263. The fatality rate was 2.38 percent.

The total number of people released from quarantine after full recoveries stood at 9,904, up 16 from the previous day.

The nation with a 50-million population has carried out 753,211 tests since Jan. 3, including 5,558 a day earlier.

Imported cases, which used to be the biggest threat for South Korea's quarantine operations before infections involving clubbers surfaced, rose by 10 to reach 1,177.  

Health authorities said they plan to ease monitoring of those who have retested positive for COVID-19 after making full recoveries. The number of such cases which reached 447 on Monday.

"There have been no secondary infections from people who have contacted the relapsed patients so far," Yoon Tae-ho, a senior health ministry official, said in a briefing. "We have not found evidence that those cases are contagious."

South Korea has been suggesting that the relapse cases were neither "reactivation" nor "reinfection" of the virus in people.

KCDC Chief Jeong Eun-kyeong echoed the view, saying those who recover from the illness will be allowed to return to their routines starting Tuesday without the need to take additional virus tests.  

On May 6, the country switched to "everyday life quarantine" and the normalization of public facilities and other business establishments, under the condition they follow basic sanitation measures. The outbreak in Itaewon, however, led to restrictions on karaoke establishments, bars, and clubs.

High school seniors will return to classrooms starting Wednesday, a week later than scheduled, and students of other grades will gradually follow suit by June 8. (Yonhap)