A total of six people have tested positive for COVID-19 after receiving the first round of vaccines in South Korea as of Monday. 

The Korea Disease Control and Prevention Agency(KDCA) said Tuesday that the six people include two nurses and one health worker at the National Medical Center whose cases had initially been reported on Monday. 

The agency did not reveal any details about the three additional people who tested positive. 

The KDCA said the six may have been infected before inoculation or before immunity was developed following the vaccination.