New virus cases bounce backed above 40 on Tuesday, as cluster infections spread to Daejeon, one of nation’s seven largest cities two hours’ drive from Seoul.

On Wednesday, Korea reported 43 new Covid-19 patients -- 31 local infections and 12 foreign arrivals -- lifting the cumulative caseload to 12,198. Fourteen patients recovered from the virus, increasing the number of cured patients to 10,774 as of midnight Tuesday, the Korea Centers for Disease Control and Prevention said.

One more person died of the new coronavirus, raising the death toll to 279, and 1,145 patients are under treatment. The nation has tested about 1.13 million suspected patients since Jan. 3.

Of the 31 locally transmitted cases, 25 cases came from Seoul, the western port city of Incheon, and surrounding Gyeonggi Province, home to half of the nation's population of 50 million. Notably, the public health authorities confirmed five new cases in Daejeon, indicating that the recent series of cluster infections may get out of the Seoul metro region and spread to the rest of the country.

Health officials took particular note of nine new virus cases in Daejeon for two days, for the first time in a month or so. As the nine patients include a Christian pastor couple and a visitor to a multilevel marketing firm’s event, chances are high that the metropolis would report additional infections.

If the new transmission continues and the daily virus curve does not flatten, the health authorities may have to apply the toughened infection preventive measures in the greater Seoul areas to the entire country.

Korea eased strict social distancing in early May, encouraged by a sharp decrease in Covid-19 cases. However, the ensuing series of sporadic cluster infections has forced the health officials to extend enhanced social distancing in the capital city and its vicinity indefinitely last Friday.

Despite unrelenting cluster infections, the KCDC cautioned against excessive fears, pointing out that the reproduction rate of Covid-19, the average number of people infected by a single patient, remains slightly above 1, down from 1.8 in the previous estimate.

Meanwhile, Korean hospitals halted their trials confirming the efficacy of chloroquine, a malaria treatment, as a possible treatment agent for Covid-19 on Wednesday.

Asan Medical Center and Gangnam Severance Hospital, the two large general hospitals in Seoul that had conducted the trial, said they recently ceased their clinical study of using chloroquine for the treatment of certain hospitalized Covid-19 patients. Earlier, the Ministry of Food and Drug Safety approved the clinical trials of chloroquine and AIDS treatment Kaletra at the two hospitals.

The announcement came after the U.S. Food and Drug Administration revoked the emergency-use authorization (EUA) of chloroquine due to potential health risks on Monday.

"The agency determined that the legal criteria for issuing EUA are no longer met," the FDA said in its release. "Based on its ongoing analysis of the EUA and emerging scientific data, the FDA determined that chloroquine and hydroxychloroquine are unlikely to be effective in treating COVID-19 for the authorized uses in the EUA."

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