Table 2. Criteria for flight-associated and possibly flight-associated secondary cases of SARS-CoV-2 infection in persons aboard a flight from Sydney to Perth, Australia, March 19, 2020.

Secondary case classification	Epidemiologic criteria	Virus WGS criteria
Flight associated	International passenger who arrived at Sydney International Airport on March 19, 2020, and transited to the flight OR domestic passenger in Australia not associated with a cruise ship before illness	Specimen yielded lineage not circulating in place of origin AND Lineage closely matched that of passengers with primary cases on flight
Possibly flight associated	Passenger on cruise ship with no known SARS-CoV-2 transmission identified	Specimen from passenger or traveling companion yielded lineage related to that of passengers with primary cases on flight
	Domestic passenger in Australia not associated with a cruise ship before illness	WGS data not available
*WGS, whole-genome sequencing.