The novel coronavirus that has been spreading in recent outbreaks in South Korea mostly belongs to a variant prevalent in Europe, North America and the Middle East, health authorities said Wednesday, and is believed to be six times as infectious as the forms of the virus that emerged from China.

From cases linked to clubs and bars in Itaewon in early May to those traced to the Sarang Jeil Church and an Aug. 15 rally in Seoul, a variant of the coronavirus known as the GH clade has been detected, according to an analysis of 685 genome samples by the Korea Centers for Disease Control and Prevention. The samples came from people who tested positive for the coronavirus.

The variants found in the genome samples during the COVID-19 outbreak in spring mostly belonged to the S clade and V clade, which were prevalent in China, where the coronavirus is believed to have originated, and other parts of Asia. The GH variant is being circulated in North America, Europe and the Middle East.

The coronavirus is largely classified into six clades, or groups of virus strains -- S, V, L, G, GH and GR -- and all the rest, according to the World Health Organization.

On Wednesday, Korea announced 320 new COVID-19 cases -- 307 locally transmitted and 13 imported from overseas -- according to the KCDC.

Wednesday’s tally, which counts cases up to midnight Tuesday, marks a jump from 280 new cases reported Tuesday and 266 Monday, after three consecutive days when it surpassed 300 -- 397 on Sunday, 332 on Saturday and 324 on Friday.

The authorities said they have yet to raise the level of social distancing to the highest in the three-tier system, which is tantamount to a lockdown, adding they will closely monitor the virus situation this week before deciding whether to further tighten social distancing rules. Currently, Level 2 social distancing rules are in place nationwide.

Residents in the Seoul metropolitan area moved around only 20 percent less over the weekend under the stricter social distancing guidelines in place, according to a government analysis based on data provided by cellphone carriers. 

Residents remained outside their own neighborhoods for more than 30 minutes on 26,762 occasions from Aug. 22-23, compared with 33,484 from Aug. 15-16. When the largest outbreak here to date hit Daegu and North Gyeongsang Province in spring, people’s movements decreased by 40 percent. 

KCDC director Jeong Eun-kyeong warned of the danger of COVID-19 transmission indoors, releasing the interim results of the epidemiological inspection into mass transmissions at a Starbucks cafe in Paju, Gyeonggi Province.

With the air conditioner on, the cafe was not ventilated properly, physical distancing was not possible due to crowding and the initial patient did not wear a mask properly while in the cafe for about two hours, she said.

In a case showing the importance of proper mask-wearing in fighting the coronavirus, all the employees at the franchise cafe, who kept their masks on at all times, avoided infection with the virus.

Among some 120 people who were on the second floor in the same time frame as the people who later tested positive, 26 people were infected as they were not properly wearing masks, according to the KCDC’s analysis of CCTV footage. A total of 66 cases, including 38 cases of secondary transmission, were reported in connection with the cafe from Aug. 12-25.

Of Wednesday’s locally transmitted cases, the vast majority, or 229, were registered in the Seoul area -- 110 in Seoul, 27 in neighboring Incheon and 92 in surrounding Gyeonggi Province.

Outside the Seoul metropolitan area, new cases were reported in all administrative regions except for Sejong, North Chungcheong Province and North Gyeongsang Province. There were 18 cases in Gangwon Province, 12 cases each in South Chungcheong Province and South Jeolla Province, seven each in Gwangju, Daejeon and North Jeolla Province, five in South Gyeongsang Province, four in Busan and two each affecting Daegu, Ulsan and Jeju Island.

Sporadic COVID-19 outbreaks continue to occur across the country, with new clusters of infections found at factories, cafes, restaurants, a public sauna, a hair salon, an apartment building, fitness centers, churches and more.

At the center of the resurgence of COVID-19 here are a Seoul-based church and a massive rally held in central Seoul on Aug. 15.

Eighteen more cases traced to the Seoul-based church were reported, with the total number of related cases coming to 933. The majority of the church-linked patients are from the Seoul metropolitan area and in their 50s or older. Some 130 cases of secondary transmission tied to the church were confirmed from 23 establishments, including schools, workplaces and hospitals, according to the KCDC.

In connection with the rally, 219 cases had been reported as of noon Wednesday, up 26 from the previous day.

Transmission routes for 18.6 percent of the new cases reported Aug. 13-26 were unidentified, according to the KCDC. In Seoul alone, 35.7 percent of the new cases reported Wednesday were from untraceable sources.

The number of new infections per day has been in the triple digits since Aug. 14, when 103 new cases were reported.

Fears over the spread of the coronavirus led to the shutdown of a record-number of schools -- 6,480 -- across the country as of Wednesday morning, according to the Ministry of Education. So far, 320 students and 81 educators had tested positive for the virus.

Of the 13 imported cases, 10 were identified while the individuals were under mandatory self-quarantine in Korea, with the other three detected during the quarantine screening process at the border. Seven cases originated in Asia, with three each from the Americas and Africa. Six of the newly diagnosed people were foreign nationals.

So far, of 18,265 people who have caught the new coronavirus, 14,368 people have been released from quarantine. Some 3,585 people are receiving medical treatment under quarantine. Forty-three people are in serious or critical condition.

Two more people died of the coronavirus, with the death toll now at 312. The overall fatality rate amounted to 1.71 percent -- 2 percent for men and 1.47 percent for women -- as of Wednesday. The fatality rate is 21.97 percent for those in their 80s or over and 7.2 percent for those in their 70s. 

The country has carried out 1,849,506 tests since Jan. 3, with 52,795 people awaiting results as of Wednesday.

By Ock Hyun-ju (laeticia.ock@heraldcorp.com)