The country added 2,008 COVID-19 cases, including 1,973 local infections, raising the total caseload to 281,938 according to the Korea Disease Control and Prevention Agency (KDCA).
The daily caseload remained in the 2,000s on Tuesday and Wednesday before falling to 1,943 on Thursday.
Daily cases have stayed above the 1,000 threshold for more than 70 days amid the fast spread of the more transmissible delta variant nationwide.
The country added three more deaths from COVID-19, raising the death toll to 2,389. The fatality rate was 0.85 percent.
Infections in the greater Seoul area, home to half of the country's population, have been a major concern for local health authorities, with nearly 80 percent of domestic cases being reported in Seoul, Gyeonggi Province and Incheon.
The authorities remained worried virus spread could further expand in other regions after the Chuseok holiday, the Korean autumn harvest celebration, when tens of millions of people are expected to travel across the country. South Koreans will have a five-day holiday period through Wednesday.
The authorities urged people to stay at home and get vaccinated to curb the spread. They will also enforce special quarantine measures, including running COVID-19 testing clinics at highway rest stops, for two weeks through Sept. 26.
The authorities earlier extended the current social distancing measures -- Level 4 in the greater Seoul area, which is the highest in the four-tier system, and Level 3 in other regions -- for another four weeks through Oct. 3.
While limiting the size of private gatherings and restaurant business hours, they have eased some restrictions to give leeway to vaccinated people.
A total of 35.41 million people, or 69 percent of the country's population, have received their first shots of COVID-19 vaccines, and 21.48 million people, or 41.8 percent, have been fully vaccinated, the KDCA said.
South Korea's COVID-19 vaccination program has been using vaccines from Moderna, Pfizer, AstraZeneca and Janssen.
The authorities said a first-shot vaccination rate of 70 percent, the country's initial inoculation goal, is expected to be achieved later Friday or Saturday. South Korea also targets to see 70 percent of the population getting fully vaccinated by end-October.
Of the newly confirmed domestic cases, 738 cases came from Seoul, 655 from Gyeonggi Province, which surrounds the capital city, and 139 cases from western port city of Incheon.
Busan, the country's second-largest city, added 51 cases, while the southeastern city of Daegu reported 38 more cases.
Imported cases, which include South Korean nationals, came to 35, up 13 from a day earlier. The total number of imported cases is now at 14,084.
Of the newly added imported cases, seven were from Uzbekistan, followed by the United States with four.
The number of patients with serious symptoms across the country reached 332, down 16 from the previous day.
The total number of people released from quarantine after making full recoveries was 254,094, up 2,056 from a day earlier. (Yonhap)
