South Korea's new coronavirus cases rose by triple digits for a fifth day Thursday, as sporadic cluster infections from private gatherings and facilities piled up across the nation, raising the possibility that the country may enhance social distancing measures.

The country added 143 more COVID-19 cases, including 128 local infections, raising the total caseload to 27,942, according to the Korea Disease Control and Prevention Agency (KDCA).

The daily caseload marked a slight decrease from 146 added Wednesday but a rise from 100 posted Tuesday.

More cities and provincial governments have raised their own social distancing schemes to curb the spread of the virus, but health authorities are considering enhancing such guidelines nationwide in the near future, as new cases have stayed above 100 for a considerable period.

South Korea, which now operates a five-tier virus curbs system, has kept social distancing at Level 1 nationwide, although some cities and government upped their virus infection preventive measures. Under Level 1, people are required to follow basic guidelines, such as wearing masks, and gatherings of over 500 people are not recommended.

Asan and Cheonan, both located in central South Chungcheong Province, adopted tougher measures last week. Wonju in Gangwon Province and Suncheon, located 415 kilometers south of Seoul, also raised their social distancing schemes to Level 1.5 this week.

People are still allowed to carry on with most of their daily routine under Level 1.5, but gatherings of 100 or more people will be regulated, though it is not a complete ban.

Health authorities believe that the current level of daily cases is manageable, but they are concerned that silent spreaders may lead to a major outbreak at anytime.

South Korea has suffered a slew of cluster infections, including those from a minor church sect in Daegu which was responsible for more than 5,000 patients earlier this year. A church in northern Seoul and an anti-government rally also had led to more than 1,700 infections.

Starting Friday, South Korea plans to slap fines of up to 100,000 won ($89) on people who do not wear protective masks in public places.

Over the past two weeks, around 35.5 percent of the newly added cases have been grouped as cluster infections, with around 13.6 percent not having clear transmission routes, the latest data showed.

Seoul accounted for 35.5 percent, followed by Gyeonggi Province with 28.2 percent, the KDCA said.

Health authorities said it was also notable that patients in their 20s and 30s accounted for more than 30 percent of the total cases, which marked a sharp rise from 22 percent in September. 

Among the locally transmitted cases, the capital city of Seoul accounted for 52 cases, and Gyeonggi Province that surrounds Seoul reported 34. Incheon, located west of Seoul, had two new patients.

The greater Seoul area houses around half of the nation's population.

South Chungcheong Province and South Jeolla Province added nine and eight additional cases, respectively. Gangwon Province and Gwangju, located 330 kilometers south of Seoul, both saw six more.

Other major cities had additional infections as well. Busan, Daegu, and Daejeon all added two new cases each.

As of Thursday noon, a total of 14 cases were traced to a military facility in Seoul. An insurance firm in western Seoul added three more cases, raising the total to 46.

Cases tied to medical facilities and senior nursing homes in Gunpo, south of Seoul, came to 143, up 10 from the previous day.

An elementary school in Pocheon, north of Seoul, reached 22, up two from Wednesday.

A church in Daegu, 302 kilometers south of Seoul, identified three more patients, raising the tally to 40.

The country added 15 imported cases.

Egypt accounted for three cases, trailed by Russia and Myanmar with two patients each. There were also imported cases from Uzbekistan, Nepal, Japan, Italy, Croatia, the United States, Kenya, and Australia.

The number of seriously or critically ill COVID-19 patients came to 53, up four from Wednesday.

South Korea reported no additional deaths, keeping the total at 487.

The number of people released from quarantine after making full recoveries stood at 25,404, up 138 from the previous day. Around 90.9 percent of the patients reported here have been cured.

South Korea carried out 2,749,772 COVID-19 tests so far, including 13,238 from the previous day.

Health authorities said they plan to hold a special meeting on the procurement of COVID-19 vaccines later in the day.

South Korea said earlier it plans to secure 10 million doses of vaccines from the COVID-19 Vaccines Advance Market Commitment (COVAX), and another batch of 20 million jabs from private drugmakers.

COVAX is a global initiative designed to work with vaccine manufacturers to provide equitable access to safe and effective vaccines to countries worldwide.

"We are currently on track to secure enough vaccines for 60 percent of the nation's population within this year," Kwon Joon-wook, deputy director of the Central Disease Control Headquarters, said without providing further details. (Yonhap)