Close contact refers to persons who have not taken adequate protection from close contact (within 1 meter) since 2 days before the onset of symptoms of suspected cases and confirmed cases, or since 2 days before the sampling were collected from asymptomatic patients. The specific contact conditions are as follows:

1) Cohabitation, study, work, or other close contacts, such as working close to one another, studying in the same classroom or living in the same house;

2) Health care workers, family members, or other people who have similar close contact during diagnosing, treating, nursing and visiting the case, such as visiting the patients or staying with the patients in a closed environment, other patients in the same ward and their caregivers;

3) People who travel in the same vehicle and have close contact, including caregivers and accompanying people (family, colleagues, friends, etc.) on the vehicle, or other passengers and stewards who are in possible close contact with cases (suspected cases, confirmed cases) and infected people (mild cases, asymptomatic infections) after investigation and evaluation;

4) People who are assessed by the field investigators as persons in contact with close contacts.

(Reference: Prevention and control of COVID-19 (Fifth Edition) issued by National Health Commission)

Source: Chinese Center for Disease Control and Prevention