South Korea's daily new virus cases dropped below 500 Sunday for the first time in four days due to fewer tests over the weekend, and health authorities plan to exempt people who were fully vaccinated overseas from mandatory two-week isolation from July.

The country reported 452 more COVID-19 cases, including 419 local infections, raising the total caseload to 147,874, the Korea Disease Control and Prevention Agency (KDCA) said.

Sunday's tally marked a sharp decrease from Saturday's 565 cases and dropped to the 400s for the first time since Tuesday, when the tally marked 454, the KDCA said.

A total of 12,372 tests were conducted across the country on Saturday, sharply down from 29,471 a day earlier, the KDCA said.

Daily caseloads here have been going through some ups and downs between the 400s and 700s in recent months with no significant signs of a letup due to sporadic cluster infections nationwide.

Health authorities said the current distancing rules will be extended until July 4.

Currently, the greater Seoul area, Daegu, Jeju Island and a few other areas are under the Level 2 distancing, the third highest in the country's five-tier COVID-19 alert system, while many other regions are under Level 1.5 amid the ban of private gatherings of five or more people.

Under the new scheme, the authorities plan to ease business curfews, with restaurants and entertainment facilities in the capital area permitted to operate until midnight, an extension from the current limit of 10 p.m.

A total of 11.8 million people have received their first shots of COVID-19 vaccines, including 386,223 the previous day, accounting for 23 percent of the country's population, since the country started its vaccination program on Feb. 26.

The KDCA said 2.99 million people, or 5.6 percent of the population, have been fully vaccinated.

Starting on July 1, people who were fully vaccinated overseas will be exempted from two-week quarantine measures when entering the country, health authorities said.

The exemption will be also granted to people who enter the country to visit family, or for the purpose of business, academics or public interest, they said.

Those who enter the country will be allowed for the two-week isolation two weeks after they get vaccines such as AstraZeneca, Pfizer, Moderna and others.

However, entrants from countries with variant COVID-19 cases, such as South Africa and Brazil, will not be subject to the exemption, they said.

The Seoul government also plans to sign agreements with nations with stable virus response measures, allowing their people to travel freely within the zone without undergoing on-arrival, two-week quarantine measures.

Meanwhile, a 38-year-old man died within four days after being administered the Janssen vaccine, the authorities said, adding that they will conduct an investigation into the case. 

South Korea is trying to inoculate 14 million people by the end of this month and 36 million by September in a move to achieve herd immunity in November, but it hopes it can reach the goal earlier than expected with the increased vaccine rollout.

In addition to vaccines from AstraZeneca and Pfizer, the country started to use the Janssen vaccine supplied by the US government for reserve forces, civil defense members and others in charge of defense and foreign affairs from Thursday.

Of the 419 new locally transmitted cases, 174 came from Seoul, 142 from Gyeonggi Province and 13 from Incheon, 40 kilometers west of the capital.

The southeastern port city of Busan, the country's second-largest city, reported 13 more cases, with the central city of Daegu reporting 14 new cases.

There were 33 additional imported cases, down seven from a day earlier, raising the total to 9,325.

The KDCA data showed the number of seriously or critically ill COVID-19 patients was 146, down nine from the previous day.

The total number of people released from quarantine after making full recoveries was 138,581, up 544 from a day earlier, the KDCA said. (Yonhap)