South Korea's new daily COVID-19 cases rose to over 420,000 Wednesday amid concerns over the continued rise in seriously ill patients and deaths over the fast spread of the highly transmissible "stealth omicron" subvariant.

The country added 424,641 new coronavirus infections, including 42 cases from overseas, bringing the total caseload to 12,774,956, the Korea Disease Control and Prevention Agency (KDCA) said.

The daily count shifted to an upturn Tuesday after five days of a constant slide, though the health authorities have said the omicron-driven worst virus wave peaked last week. The number of daily infections soared to as high as 621,197 on March 17.

High infections have pushed up COVID-19 deaths and serious cases.

The country added 432 new COVID-19 deaths Wednesday, which is the second-largest daily figure ever after 469 single-day deaths reported Thursday. The fatality rate stood at 0.12 percent.

The number of critically ill patients rose by 86 to an all-time high of 1,301, the KDCA said. The previous record was set Monday when the figure came to 1,273.

Serious cases rose to above 1,000 earlier this month and have since been above the level. The KDCA said the number of deaths and serious cases could grow further in the coming weeks.

The health authorities have also been leery of a possible upturn, as the even more transmissible BA.2 "stealth omicron" subvariant became the dominant strain in the country and continued to have spread fast.

The strain accounted for 56.3 percent of the total infections last week.

As of Tuesday, 32.69 million people out of the total population, or 63.7 percent, had received booster shots. The number of fully vaccinated people came to 44.48 million, representing 86.7 percent, the KDCA said.

Starting Thursday, the government will begin administering COVID-19 vaccine shots to children aged between 5 and 11. Around 3.15 million are in this age group.

A growing number of local clinics are expected to provide face-to-face treatment to COVID-19 patients, as the government on Wednesday began accepting applications at smaller clinics for the medical service.

The move aims to better support at-home patients and to move on to a fresh medical response system to handle the prolonged pandemic, the KDCA said.

Currently, the government has designated 279 clinics across the country as facilities reserved for at-home patients, but calls have grown for their expansion in line with the surge in total infections and the subsequent rise in patients staying at home.

Eyes are on the government's planned announcement of its decision Friday on whether to adjust current social distancing rules.

The government has relaxed some social distancing rules in efforts to regain normalcy and support small businesses hit hard by the pandemic.

Currently, the government enforces an eight-person cap on private gatherings and an 11 p.m. business curfew, and those curbs are to expire Sunday. (Yonhap)