Novel coronavirus infection cannot be detected by routine blood tests and patients need to undergo viral nucleic acid sequence testing. Nucleic acid testing is performed on patients with throat secretions or sputum, and the virus can usually be detected during the incubation period. Based on experience and information about the case, the period of medical observation should be 14 days for those who are in close contact with the patient. Close contacts living with the patient can be clinically diagnosed as infected when they test positive for nucleic acid, and there is no need to go to the CDC for a repeat nucleic acid test at this time.