Who is a close contact in China?

It is important to note that the information provided in this Series is intended for your general knowledge only and is not a substitute for professional medical advice or treatment.

The Chinese National Health Commission, in the Protocol on Prevention and Control of COVID-19 (Edition 6), defines close contacts as "people who had unprotected close contact with a confirmed or suspected case within two days prior to symptom onset or with an asymptomatic carrier within two days before sampling".

Specific types of close contacts include: (1) anyone working, living, studying together with a patient or having close contact with a patient in other locations; (2) healthcare workers directly conducting diagnosis and treatment, family members caring for or visiting a patient, or anyone having similar short-distance contact; (3) passengers taking the same transportation vehicle and having short-distance contact with an infected person; (4) other persons meeting criteria for close contacts as investigated and assessed by onsite investigators. As for the determination of close contacts taking the same vehicle, the specific criteria are different for airplane, train, automobile, and steamship.

The guidelines above are excerpted from the Protocol on Prevention and Control of COVID-19 (Edition 5 and 6) and are subject to alteration. Health authorities have been updating and improving these guidelines with increased knowledge on the virus. There have been four major changes in defining close contacts.

First, the scope of infectious sources was expanded to include asymptomatic carriers.

Second, the types of close contacts were gradually specified but are not exhaustive given the limited knowledge on the virus.

Third, short distance was originally defined as "within 1 meter" but was removed in subsequent versions.

Fourth, while there is no definition regarding the length of time of contact, a specific timing point was incorporated to be two days prior to the onset of symptoms for suspected and confirmed cases or two days prior to sampling for an asymptomatic case.

To reduce infection risks, China has been using a broad set of criteria in defining close contacts. Management of close contacts is an important means to prevent further spread of the disease, and gradual updates of the criteria is part of the most comprehensive, strictest and most thorough prevention and control strategy that China has been taking.

Author: Xu Puheyan, Center for International Knowledge on Development