The South Korean government plans to enforce guidelines for densely populated workplaces, stung by mass coronavirus infections at a call center in Seoul.

At least 90 people, including 77 employees at a call center in Guro-gu and 13 people who came into contact with them, tested positive for COVID-19 as of Wednesday afternoon, making it the biggest cluster of infections in Seoul that is home to 9.7 million people.

The country’s coronavirus cases as of midnight Tuesday came in at 7,755, up 242 cases from the previous day, according to data from the Korea Centers for Disease Control and Prevention. The death toll rose by six to 60.

In Seoul’s largest-ever cluster of infections, the patients worked together at the call center on the 11th floor of a 19-story building in Guro-gu, southeastern Seoul, according to the health authorities, with the tests and an epidemiological study on 207 employees on the same floor underway as of Wednesday afternoon.

“Testing is underway, so the number of cases could further grow,” said KCDC Director Jung Eun-kyeong at a briefing.

Some 553 people, who work at the same call center but on different floors, were placed under self-quarantine to be tested for the virus.

Fears about community spread are growing as some of the employees at the call center continued their daily routine until recently after they began to show symptoms in late February. How the virus was first transmitted to the employees also remains unidentified.

A 48-year-old patient started showing symptoms of infection Feb. 29 but continued her daily routine until she tested positive Tuesday. She used public transportation between March 2-6 to go to the office located nearby the capital’s transport hub, Sindorim Station. She visited a hospital for treatment on March 2 and 4. She had after-work dinners with coworkers on March 5, according to the inspection by the health authorities.

The employees and confirmed patients at the call center reside in different parts of Seoul, its surrounding Gyeonggi Province and Incheon, with the municipal leaders vowing a joint response to contain the spread of the virus.

Some 21 percent of the patients had used public transportation, according to the Seoul Metropolitan Government.

Jung pointed out that it is difficult to track people who might have been exposed to the virus while commuting in public transportation packed with unidentified crowds. Keeping the overall level of sanitization high is the best way to mitigate the spread, she added. 

Among those working at the call center, there were five followers of the fringe religious sect the Shincheonji Church of Jesus, which is at the heart of the country’s virus outbreak, but all of them tested negative as of Wednesday afternoon.

The packed working environment at the call center, where employees sit close to each other in confined spaces and constantly talk on phones, is believed to have made it easier for the virus to spread.

Daegu, which has already been hit hardest by the virus outbreak, also saw 10 employees at six call centers in the city test positive for the virus, according to the municipality.

Through the guidelines, the government will encourage businesses with packed environments -- including call centers, educational institutes, fitness centers, nightclubs and karaokes -- to allow remote working and adopt flexible work hours, and to reduce human density by adjusting seating arrangements.

Of the 242 new cases confirmed Wednesday, 52 were reported in Seoul and 12 each in Incheon and Gyeonggi Province. Most were linked to the call center in southwestern Seoul.

The call center case shows that the virus may have been spreading undetected in the country’s most populated areas and this time it may be harder to contain, experts say.

“So far, there have been hospitals and churches so the spread of the virus could be controlled to some extent,” said Kim Woo-joo, a professor of medicine at Korea University Guro Hospital who specializes in infectious disease.

“But in the case of the call center, there are many employees, who were confirmed to be infected days after they showed symptoms, which means those around them and many public transportation commuters could have been exposed to the virus already,” Kim said.

There were 131 new cases in the southeastern city of Daegu, the city worst hit by the virus outbreak, along with 18 in North Gyeongsang Province, according to the data. The cases in the region represent 90 percent of the country’s total.

Some 80 percent of the country’s total cases have been linked to infection clusters, 69.9 percent of which can be traced to the Daegu branch of the Shincheonji Church of Jesus, according to the KCDC.

The increase in cases in the country is driven by emerging clusters of infections involving medical facilities, social welfare facilities, religious facilities and workplaces, the agency said. 

So far, 60 people, mostly those in their 60s or older with underlying illnesses, have died from COVID-19 here, with the overall fatality rate at 0.77 percent. The death rate here stands at 4.35 percent for those in their 70s and 7.2 percent for those in their 80s.

As the number of cases is soaring in Italy and Iran, the government said it will step up health checks on those who enter Korea from the countries, requiring them to get fever checks and fill out forms on their health conditions.

The move came after a 24-year-old man who arrived here after visiting Italy last week tested positive for the virus Tuesday.

A total of 7,407 people confirmed with novel coronavirus remain in q
uarantine, while 288 people have been released after making full recoveries.

The number of people awaiting test results for the virus stood at 18,540. The country has so far tested a total of 214,640 people, with 196,100 testing negative as of Tuesday midnight.

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