Close contacts are suspected cases, confirmed cases and positive surveillance contacts to meet one of the following conditions, but did not take effective protection: 1, and cases living, studying, working or other close contacts; 2, treatment, care, visiting cases of health care workers, family members or other similar close contact with the case; 3, the same transport and close contact with the case, including those who have cared for the patient on the transport, the patient’s peers, other passengers and crew members found to be in close contact with the patient after the investigation and assessment.