The new coronavirus outbreak in Seoul, a city of 9 million, is feared to grow after an infection cluster was identified Monday at a call center in a heavily trafficked district in Guro.

Health officials said one of the workers who tested positive for the virus started having symptoms as early as Feb. 22 before being diagnosed this week. The confirmed cases linked to the call center numbered 102 as of Thursday morning, according to the mayor’s office.

At 174, Seoul has the highest number of confirmed cases outside Daegu and North Gyeongsang Province, the country’s two most adversely affected regions.

Korea Centers for Disease Control and Prevention data shows 96.8 percent of beds at coronavirus-only hospitals in Seoul equipped with negative pressure rooms are occupied as of Monday. The nationwide figure stands at 89.4 percent.

Choi Jae-wook, a preventive medicine specialist at Korea University Hospital, says Korea’s virus tally may fail to reflect the outbreak’s full picture, as the testing program has so far mainly targeted those with ties to Daegu or Shincheonji.

“It’s highly likely other potential patients who haven’t been tested are out there, and the blow will be especially harsh for a dense city like Seoul,” he said.

In Daegu -- whose cases account for 75 percent of the national occurrence --, at least four people have died while in home isolation due to a bed shortage, with 1,138 still waiting to be admitted at hospitals as of Wednesday.

To increase availability of beds, the Health Ministry said patients would be classified into four severity levels to give those in more critical condition priority in getting a hospital bed.

For virus patients with milder symptoms, the ministry has set up 15 care centers with a combined bed capacity of 3,300 in the Gyeongsang and Chungcheong provinces, where they can stay in isolation under the watch of health care personnel. A Seoul care center is slated to open next week.

But as more patients are getting severely ill, experts say the city could run out of critical-care facilities such as ventilators.

KCDC said as of Thursday, 93 patients are critically ill, 59 of whom are unable to breathe without assistance. This is a 16.2 percent increase from just two days ago.

Pulmonologist Chun Eun-mi of Ewha University Medical Center in southwestern Seoul said access to mechanical ventilators was only available at intensive care units, which run at nearly full occupancy even during a non-emergency.

“There aren’t many vacant ICU beds, even at big hospitals in Seoul, and ICUs can’t be built in a short period of time,” she said. “If patients in high risk groups aren’t moved to an ICU at the right time, the number of casualties will rise.”

Former director of KCDC Jun Byung-yool said the health authorities should be wary not to repeat the mistakes made in Daegu.

“Hospitals should be supplied with care facilities using the government budget,” he said. “Preemptive measures are needed before the number of patients rise further in Seoul and the surrounding metropolitan area.”

By Kim Arin (arin@heraldcorp.com)