According to the Korea Centers for Disease Control and Prevention, 14 people who had been placed under quarantine -- including flight attendants and passengers on the same plane as the patient, medical staff and immigration officials -- have all tested negative for the disease.

Also, the authorities are keeping close tabs on 21 people who came in close contact with the MERS patient.

If they test negative again, all will be released as of Sept.

22 as the maximum incubation period for secondary cases associated with limited human-to-human transmission of MERS is approximately 14 days, the KCDC said.

The agency said that 424 people who came into ordinary contact with the MERS patient are currently being monitored. They have not been quarantined, but they have to report their health conditions every day to officials in charge of monitoring.

MERS is a viral respiratory disease with a fatality rate of 20-46 percent. It is caused by a novel coronavirus carried by camels and can be spread when someone is in close contact with a patient for a sustained period.

South Korea was hit by an outbreak in 2015, resulting in 38 deaths and 186 people testing positive for MERS. (Yonhap)