Four out of 106 novel coronavirus patients in South Korea have shown abnormal responses after being administered with remdesivir, an experimental drug conventionally used for Ebola, health authorities here said Tuesday.

The medication developed by US pharmaceutical giant Gilead Sciences Inc. has been supplied to 108 COVID-19 patients in critical condition since early July, according to the Korea Centers for Disease Control and Prevention (KCDC).

Four of them have shown side effects, such as an elevation in the liver somatic index and a skin rash, the KCDC said. It did not elaborate on the two others.

"Those who have been administered with remdesivir are mostly elders with underlying diseases," Kwon Jun-wook, deputy director of the Central Disease Control Headquarters, told a press briefing. "Another probe is under way to determine the exact efficacy of remdeisivir."

Coronavirus patients who need oxygen treatment, such as extracorporeal membrane oxygenation (ECMO), have been administered the drug in 33 hospitals across the country, the KCDC said.

In June, South Korea's drug safety watchdog approved the use of remdesivir as a treatment drug for the new coronavirus, allowing for the drug's special importation.

The first batch of the antiviral drug was donated by Gilead Science. The KCDC plans to begin talks to purchase more, with details of the imported amount and price not to be disclosed.

Gilead Sciences earlier announced it will provide remdesivir at $390 per vial for direct purchase by the United States and other developed countries.

COVID-19 patients here do not pay for the drug, as the country covers the cost of treating the infectious disease under the related law.

Coronavirus patients are given six vials of remdesivir over five days, which amounts to $2,340 per patient for a typical regimen. If necessary, the drug can be administered for another five days.

The country identified 34 more cases of COVID-19 on Tuesday, raising South Korea's total cases to 14,423, according to the KCDC. (Yonhap)