South Korea's daily new coronavirus cases stayed in the 600s for the second straight day Friday as the country's virus fight is at a critical juncture of bracing for another wave of the pandemic.

The country reported 673 more COVID-19 cases, including 652 local infections, raising the total caseload to 112,789, the Korea Disease Control and Prevention Agency (KDCA) said.

Friday's daily caseload was down from 698 on Thursday and 731 on Wednesday, which marked the highest since Jan. 7.

The country added two more deaths, raising the total to 1,790.

Health authorities cautioned against a hike in group infections in various settings, including sports facilities, churches, karaoke businesses, restaurants, workplaces and schools, as people have increased their activities in the spring.

Concerns have been rising over a further spike in new cases as the proportion of untraceable viruses stood at 28.2 percent over the past week, complicating efforts to contain the spread of the virus.

Officials warned of tougher rules on multiuse facilities and business operations if the current trend continues.

Last week, the country decided to maintain the current level of social distancing rules through May 2 to contain the virus, while banning operations of entertainment establishments in the greater Seoul area and the southeastern port city of Busan.

The greater Seoul area, home to half of the nation's 52 million population, is under the Level 2 distancing scheme, the third highest in the five-phase system. The rest of the country is under Level 1.5, except for some municipalities that have adopted Level 2 measures.

Restaurants in the capital area are allowed to have dine-in customers until 10 p.m. under the current guidelines, but officials said they could shorten their business hours if daily cases rise further.

To detect patients at an early stage, health officials said they will expand preemptive testing to detect patients and explore ways to effectively use self-testing kits to further step up the testing capacity.

Since the country started its vaccination program on Feb. 26, a total of 1,379,653 people have been given COVID-19 vaccine shots, including 92,660 the previous day.

AstraZeneca's vaccine has been given to 971,984 people, while 407,669 received that of Pfizer.

The KDCA said 60,571 people have received two doses.

A total of 12,013 cases of side effects after vaccinations have been reported, up 86 from a day earlier, but 98.4 percent were mild symptoms, including muscle pain and fever.

One more death after vaccinations was reported, raising the total to 52, according to the KDCA. Authorities, however, said most cases were not related to the vaccination.

South Korea plans to vaccinate 12 million people by the end of June and achieve herd immunity by November, but concerns are rising over delays in the inoculation drive after the US suspended the use of the Johnson & Johnson vaccine over rare blood clots.

With only two types of vaccines currently available here, the health ministry earlier said it expects to secure Novavax vaccines as early as June, and 20 million doses will be ready by the third quarter. Novavax vaccines require two shots for immunization.

Of the newly confirmed locally transmitted cases, 215 came from Seoul, with Gyeonggi Province that surrounds the capital city accounting for 216.

The southeastern port city of Busan reported 44 new cases.

There were 21 additional imported cases.

The number of seriously or critically ill COVID-19 patients was 111, up 12 from the previous day.

The total number of people released from quarantine after making full recoveries was 103,602, up 549 from a day earlier. (Yonhap)