On May 12, the Central Epidemic Command Center (CECC) reported that multiple infections linked to workplace and family clusters and local cases of unknown sources of infection had been reported in Singapore recently. The CECC also pointed out that there had been a cumulative total of over 450 local confirmed cases in Vietnam since April 29. Therefore, the CECC will move Singapore and Vietnam to its list of medium-risk countries from low-risk countries, effective immediately.