South Korea's daily new COVID-19 cases remained under 400 for the second day Tuesday on fewer tests over the weekend as the country's vaccination drive picks up steam with one in four South Koreans receiving at least one jab.

The country reported 374 more virus cases, including 347 local infections, raising the total caseload to 148,647, the Korea Disease Control and Prevention Agency (KDCA) said.

The latest tally is down from 399 cases on Monday and 452 on Sunday, and marks the lowest since March 23, when the country reported 346 cases.

The country added four more deaths, raising the death toll to 1,992.

Health authorities are set to implement a revamped social distancing scheme next month after extending the current distancing rules until July 4.

Currently, the greater Seoul area, Daegu and Jeju Island are under the Level 2 distancing, the third highest in the country's five-tier system, while other regions are under Level 1.5 with nationwide restrictions on private gatherings of five or more people.

Under the revamped four-tier scheme, 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 restrictions until 10 p.m.

Health authorities said they will announce the revamped distancing rules set to be implemented next month this coming Sunday.

The country has already eased some restrictions ahead of the new virus restrictions, allowing outdoor sports venues under Level 2 to fill 30 percent of their seating capacity since Monday, compared with the previous 10 percent.

The country's vaccination campaign has also accelerated, with health authorities aiming to inoculate up to 14 million people with at least one vaccine dose by the end of this month and 36 million, or around 70 percent of its population, by September to achieve herd immunity in November.

Health authorities said in a briefing that the country has inoculated 13 million people with at least one vaccine dose as of 2:30 p.m. Tuesday. The country launched its vaccination campaign in late February.

South Korea currently administers two-part vaccines from AstraZeneca and Pfizer as well as Janssen's single-dose vaccine.

Health authorities said inoculations with Moderna's vaccine will start this week once its approval process is completed later in the day.

The country received 55,000 doses of Moderna's two-part vaccine earlier this month, which will be used to inoculate medical workers aged below 30.

Health authorities also said that they are currently not considering prioritizing vaccinations for workers in the country's key industries, such as the semiconductor sector.

The country added 226 cases of major variants of the virus, raising such cases to 1,964 in total since December last year when it began testing for the strains.

Health authorities identified 192 additional cases of the British variant, 30 cases of the Indian strain, also known as the Delta variant, three cases of the South African variant and one case of the Brazilian variant.

Health authorities acknowledged that the Delta variant is more transmissible but added that complete vaccinations can protect against the strain, citing British analysis.

Of the 347 newly confirmed locally transmitted cases, 128 came from Seoul, 118 from Gyeonggi Province and 11 from Incheon, 40 kilometers west of the capital.

There were 27 additional imported cases, raising the total to 9,391.

The total number of people released from quarantine after making full recoveries was 139,733, up 711 from a day earlier. (Yonhap)