The daily number of new coronavirus cases in South Korea stayed in the 400 range for the third day in a row Tuesday, but health authorities say the next few days may be critical in the virus fight amid concerns over a third infection wave coming with the winter season.

The country added 451 more COVID-19 cases, including 420 local infections, raising the total caseload to 34,652, according to the Korea Disease Control and Prevention Agency (KDCA). It reported no additional coronavirus fatalities, bringing the total to 526.

The daily virus tally is on a slowing path after peaking at an eight-month high of 581 last Thursday. An average of 480 daily new cases was reported over the past week.

The authorities, however, said they have to assess the trend for several more days before judging whether the daily new cases in the 400 range are on a clear downward path.

They have repeatedly warned of a possible surge in the upcoming winter season, urging people to follow elevated antivirus measures.

The greater Seoul area that includes Seoul, the surrounding Gyeonggi Province and the western port city of Incheon is under Level 2 social distancing measures in its five-tier system, but even tighter restrictions are applied to virus-prone facilities.

All other areas are at Level 1.5 distancing measures, up one notch, for two weeks.

Under the tougher distancing measures, saunas and steam rooms in bathhouses are not allowed for one week in the greater Seoul area. Nine kinds of indoor exercises practiced in groups, including Zumba dancing, aerobics and kickboxing, are also banned

Hotels, party rooms and other guesthouses that host year-end or New Year's parties that are known be prone to virus transmission are also banned.

Medical experts, however, urged the health authorities to consider elevating the social distancing system by one notch to Level 3, as toughened measures are more effective than implementing other steps in reining in the current spreading pace.

"The public is very confused as authorities break down the social distancing level, such as 1.5 and 2.5," the Korean Medical Association (KMA) said in a press release. "Social distancing is the most effective way to stop the spread of COVID-19 infections."

By region, 153 new virus cases were reported in Seoul, 86 cases in Gyeonggi Province that surrounds the capital and 16 cases in Incheon, west of Seoul, accounting for more than 60 percent of the daily new locally transmitted cases. The greater Seoul area is home to around half of the nation's 51.6 million population.

Other municipalities reported new infections, with the southern port city of Busan and North Chungcheong Province each adding 31 new cases.

Busan newly reported 46 COVID-19 patients, which were not yet reflected in the KDCA official tally released earlier in the day.

Among virus clusters, a dance academy in western Seoul added 26 more cases, bringing the total to 215, while a sports facility in Seoul's Nowon Ward, reported five additional cases, raising the total to 15.

An additional 12 people tested positive in cases traced to a singing class in Gyeongsan, raising the total to 37, the authorities said. An additional 29 people tested positive in cases traced to a religious facility in Busan, raising the total caseload to 30.

The number of seriously or critically ill COVID-19 patients came to 97 as of midnight, sharply up from 72 a day earlier.

The country added 31 imported cases coming mainly from the United States and Asian countries, excluding China, the KDCA said.

The total number of people released from quarantine after making full recoveries stood at 27,885, up 260 from the previous day. (Yonhap)