Prime Minister Kim Boo-kyum said on Thursday that the new measures will be enforced for at least 16 days after taking effect on Saturday, saying there's an urgent need to bring the country to a "standstill" with the delta-driven surge overwhelming stretched hospitals and exhausted medical workers.
Schools in the densely populated capital Seoul and nearby metropolitan areas, where the virus has hit hardest, will also go back to remote learning after fully reopening in November.
The Korea Disease Control and Prevention Agency reported 7622 new cases on Thursday, close to the daily record of 7850 set a day earlier. That brought the national caseload to 544,117, with nearly 97,000 added in December alone.
Most of the transmissions were in the capital region, where officials say more than 86 per cent of intensive care units designated for COVID-19 treatment are already occupied amid a spike in hospitalisations and deaths.
More than 890 virus patients died this month, bringing the country's death toll to 4518. As of Thursday morning, a record 989 patients were in serious or critical condition.
"During this period of standstill, the government will reinforce the stability of our medical response capabilities," said Kim, Seoul's No. 2 behind President Moon Jae-in, during a virus meeting. "We ask our people to respond to these efforts by actively getting vaccinated."
The viral surge has been a huge setback for President Moon Jae-in's government, which had significantly eased social distancing rules in November while declaring a phased return to pre-pandemic normalcy.
While focusing on improving the economy, officials had predicted that the country's rising vaccination rates would keep hospitalisations and fatalities down.
But there has been a surge in serious cases among people in their 60s or older, including those whose immunities have waned after getting inoculated early in the vaccine rollout that began in February.
More than 81 per cent of the population of over 51 million has been fully vaccinated, but only 17 per cent of people have received booster shots.
After hesitating for weeks, officials moderately tightened social distancing rules last week, banning gatherings of seven or more people in the Seoul metropolitan area and requiring adults to verify their vaccination status to use restaurants and other businesses, but such measures didn't meaningfully slow the virus' spread.
Jung Eun-kyeong, KDCA's commissioner, said the country could see daily infections exceed 10,000 or 20,000 in the coming weeks if it fails to meaningfully slow transmissions now.
She said that would push the number of serious cases to between 1600 and 1900, possibly beyond what hospitals could handle without sacrificing their non-COVID-19 care.
Health Minister Kwon Deok-cheol said the four-person gatherings limit will only be applied to fully vaccinated adults.
Those who aren't fully vaccinated will be required to eat alone at restaurants, Kwon said. The rules won't be applied to children 18 years or younger.
Restaurants, coffee shops, gyms and karaoke venues will be required to close at 9pm, while movie theatres, concert halls and private cram schools will have to close at 10pm.
