Over 600 South Koreans diagnosed with COVID-19 have been treated with remdesivir so far amid suspicions over the efficacy of the experimental medicine. 

Global media outlets on Thursday cited a World Health Organization study which said the antiviral drug has little or no effect on mortality and the length of hospitalization. 

Originally developed by U.S. pharmaceutical giant Gilead Sciences to combat the Ebola virus, remdesivir was previously known to be effective in stopping the propagation of COVID-19 in infected people.

South Korean health authorities approved its use in June as an emergency treatment for COVID-19 patients and began to administer the drug the following month. 

According to the Korea Disease Control and Prevention Agency(KCDA), a total of 611 South Korean coronavirus patients have been given the drug as of Thursday. Among them, 11 cases of adverse effects, including liver dysfunction and rash, were reported.