South Korea's daily new coronavirus cases fell back to the 400s on Sunday for the first time in 20 days amid continued cluster infections and growing fears over the spread of more virulent variants.

The country reported 480 more COVID-19 cases, including 464 local infections, raising the total caseload to 139,910, the Korea Disease Control and Prevention Agency (KDCA) said.

It marks the first time that the new caseload fell below 500 since May 10 when 463 cases were reported. The drop is believed to be partly due to fewer tests conducted over the weekend.

There were six additional fatalities, raising the death toll to 1,957. The fatality rate was 1.4 percent.

Daily caseloads stayed between the 500s and the 700s last week. After soaring in December, they have not let up due to continued community infections.

In a bid to contain the spread of the virus, the government plans to maintain bans on private gatherings of five or more people for the time being.

But it will loosen the current social distancing measures in July if the average daily caseload remains below 1,000 and at least 13 million people, accounting for 25 percent of the country's total population, have been inoculated by the end of June.

The country also plans to vaccinate 36 million by September in order to achieve herd immunity in November.

A total of 5.4 million people, including 163,457 the previous day, have received their first shots of COVID-19 vaccines since the country started its vaccination program on Feb. 26.

AstraZeneca's vaccine has been given to 3.27 million people, while 2.13 million have received that of Pfizer.

The KDCA said 2.14 million people have been fully vaccinated, with an additional 8,532 receiving their second jabs the previous day.

People who have gotten their first shots will be allowed to take their masks off outdoors starting in July.

The country also started to allow younger people who are not yet officially eligible to receive shots to apply for no-show vaccines through popular mobile platforms Thursday.

Health authorities plan to announce details of their plan at 4:30 p.m. to provide 550,000 South Korean soldiers with vaccines from the United States.

The authorities will give a briefing on when the vaccines will arrive, what kind of vaccines will be provided and the inoculation schedule for the soldiers.

During his summit with South Korean President Moon Jae-in on May 21, US President Joe Biden said his country will provide vaccines to all South Korean soldiers.

Of the 464 new local infections, 333 cases came from the capital area, with 159 from Seoul, 156 from Gyeonggi Province and 18 from Incheon, 40 kilometers west of the capital.

There were 16 additional imported cases, down 12 from a day earlier. The country's total number of imported cases is now at 9,034.

Health authorities are especially keeping close tabs on COVID-19 variants from overseas that are believed to be more contagious.

The number of seriously or critically ill COVID-19 patients came to 150, down 10 from the previous day.

The total number of people released from quarantine after making full recoveries was 130,381, up 642 from a day earlier, with 7,572 people being isolated for COVID-19 treatment, down 169 from a day ago. (Yonhap)