South Korea's daily new coronavirus cases exceeded 500 for the fifth straight day on Sunday, putting health authorities on alert over another potential wave of virus infections amid spring weather.

The country reported 543 more COVID-19 cases, including 514 local infections, raising the total caseload to 105,279, the Korea Disease Control and Prevention Agency (KDCA) said.

The country added four more deaths from COVID-19, increasing the total to 1,744.

The daily virus cases have stayed above 500 since Wednesday.

A third wave of infections here, which began in mid-November last year, has shown little sign of slowing down, with the daily cases having recently stayed in the 300-400s for more than a month after peaking at a record high of 1,241 on Dec. 25.

Health authorities warned of another wave as cluster infections at various facilities, including saunas, hospitals and workplaces, continued. The movement of people has also risen amid warm spring weather.

The KDCA called for people to strictly abide by distancing rules over the Easter weekend and during this week's by-elections in Seoul and the second-biggest city of Busan.

To contain further spread of the virus, the Level 2 social distancing rules have been extended in the greater Seoul area, home to half of the country's 51.7 million population, for another two weeks until April 11. The rest of the country will be put under Level 1.5 for the same period.

Under Level 2, gatherings of five or more people are banned, while restaurants and other public facilities are allowed to remain open till 10 p.m.

Since the country started its vaccination program on Feb. 26, a total of 962,083 people have been given COVID-19 vaccine shots, including 27,298 the previous day. The KDCA said 1.85 percent of the population has received a first shot.

AstraZeneca's vaccine has been given to 855,929 people, while 106,154 received that of Pfizer.

A total of 11,018 cases of side effects after vaccinations have been reported, but 98.6 percent were mild symptoms including muscle pain and fever

A total of 32 deaths after vaccinations have been reported, according to the KDCA.

South Korea aims to achieve herd immunity by November.

Of the locally transmitted cases, Seoul reported 146 new cases, and Gyeonggi Province that surrounds the capital city identified 146 new patients. The southern port city of Busan reported 60 more cases.

Cases tied to a distribution center in Incheon, west of Seoul, reached 30, up six from the previous day.

A religious facility in Goyang, north of Seoul, reported 21 cases, up 20 from a day earlier. Infections traced to a bar in Busan added 33 to 233.

The number of new imported cases came to 29, raising the total to 7,679.

The number of patients with serious symptoms across the country reached 99, down from 101 the previous day, the KDCA said.

The total number of people released from quarantine after making full recoveries moved up 393 to 96,589. (Yonhap)