South Korea introduced a new five-tier social distancing system on Sunday to make the government’s antivirus response more quick, effective and sustainable amid the prolonged COVID-19 pandemic.

In what Prime Minister Chung Sye-kyun called “meticulous antivirus response,” the level of antivirus restrictions will be divided into five stages, from the previous three, depending on the scope and magnitude of the virus spread. Also restrictions will be customized for different facilities and regions depending on levels of risks and circumstances.

This comes as the government seeks to break away from a nationally unified, unilateral approach in its virus response as most COVID-19 infections in Korea are concentrated in Seoul metropolitan area, home to nearly half of the country’s population.

Different levels of antivirus restrictions – including a limit on the number of people allowed to gather, a ban or restriction on operation of businesses and closing of schools – will come into force in accordance with the level of social distancing rules employed by the central government.

However, under the two lowest levels of the virus alerts, which are issued when the virus spreads in limited areas rather than nationally, municipalities are given full discretion in their handling of the situation. This means that businesses and schools can stay open in areas less affected by the virus, while operations are restricted in other parts of the country.

In adjusting the level of antivirus restrictions, key indicators are the weekly pattern of infections and hospital capacity to accommodate patients in critical condition. Other indicators include the number of patients aged over 60 and the R number -- average number of secondary infections produced by a single infected person.

Korea reported a triple-digit increase in new COVID-19 cases for the fifth straight day Sunday, amid concerns over a possible surge in infections in the aftermath of a Halloween weekend that drew large crowds to major nightlife spots.

Korea reported 124 new coronavirus cases -- 101 cases locally transmitted and 23 imported from overseas -- in the 24 hours ending Saturday at midnight, according to the Korea Disease Control and Prevention Agency.

A new cluster of infections was found at a high school in central Seoul, with a total of 16 related cases. The first case was reported Thursday.

The country continues to see an uptick in cases traced to nursing homes, hospitals, a welfare facility, a church, a public sauna and social gatherings -- mostly in the Greater Seoul area, which has been leading the daily tally that is fluctuating around 100 over the past weeks.

Of Sunday’s locally transmitted cases, the majority were in Greater Seoul -- 45 in Seoul and 36 in Gyeonggi Province, which surrounds the capital. Nine cases were posted in South Chungcheong Province, with three each in Gangwon Province and South Jeolla Province, two each in South Gyeongsang Province and Daegu and one in North Chungcheong Province.

Korea reported 23 imported cases. Among them, nine were identified while the individuals were under mandatory self-quarantine in Korea, with the other 14 detected during the screening process at the border. Nineteen cases were from elsewhere in Asia, three came from Europe and one was from the United States. Twelve of the imported cases involved foreign nationals.

The number of COVID-19 patients in serious or critical condition here marked 51.

Two more people died from the virus, bringing the death toll to 466. The overall fatality rate is now 1.75 percent.

So far, of the 26,635 people confirmed to have contracted the new coronavirus here, 24,357 have been released from quarantine upon making a full recovery, up 46 from a day earlier. Some 1,812 people are receiving medical treatment under quarantine.

The country carried out 6,138 tests in the past day. A total of 24,838 people were awaiting results as of Sunday.

By Ock Hyun-ju (laeticia.ock@heraldcorp.com)