Dates in effect	Definition of confirmed case	Definition of confirmed non‐case	Definition of suspect case	Role of serology in testing
16‐17 January 2020 (version 1)	Cases (not confirmed cases) defined as virus genome highly homologous to coronaviruses	Not defined	Observation cases: defined as combination of exposure in Wuhan and symptoms focused on pneumonia, leukopenia and lack of improvement	No role
18 January‐2 March (versions 2, 3, 4, 5, 5 revised, and 6)	Suspect cases with either real‐time fluorescent RT‐PCR indicates positive for new coronavirus nucleic acid; OR viral gene sequence is highly homologous to known new coronaviruses	Suspect cases can be ruled out after 2 consecutive negative respiratory tract nucleic acid tests taken at least 24‐hours apart.	Suspect cases: combination of exposure (such as residence in/travel to Wuhan or exposure to a confirmed case within 14 days of onset) AND clinical features (such as symptoms: fever, respiratory symptoms, and tests: chest imaging, white blood cell and lymphocyte count). Exact definition varies slightly with version.	No role
3 March‐present (version 7)	Suspect cases with either real‐time fluorescent RT‐PCR indicates positive for new coronavirus nucleic acid; OR viral gene sequence is highly homologous to known new coronaviruses; OR NCP virus‐specific IgM and IgG are detectable in serum; NCP virus‐specific IgG is detectable or reaches a titration of at least 4‐fold increase during convalescence compared with the acute phase.	Suspect cases can be ruled out after 2 negative NAATs, taken at least 24‐hours apart, and the NCP virus‐specific IgM and IgG are negative after 7 days from onset	Suspect cases: combination of exposure (such as residence in/travel to Wuhan or exposure to a confirmed case within 14 days of onset) AND clinical features (such as symptoms: fever, respiratory symptoms, and tests: chest imaging, white blood cell and lymphocyte count)	Part of definition of cases and confirmed non‐cases
NAAT: nucleic acids amplification test; NCP: novel coronavirus pneumonia; RT‐PCR: reverse transcription polymerase chain reaction; Source: CDC China 2020 .