Table 1.

Definition of close contacts.

Setting	Definition
Airplane setting	Aircraft passengers in the same row and the two rows in front and behind a symptomatic case.
Household setting	Prolonged (>15 min) face-to-face contact with the confirmed case during the illness in a household setting.
Household setting who also visited the patient in hospital	As above and hospital visiting.
Healthcare setting	(i) Healthcare worker (HCW) who provided direct clinical or personal care to or examined a symptomatic confirmed case or was within close vicinity of an aerosol-generating procedure AND who was not wearing full personal protective equipment (PPE) at the time; or (ii) a visitor to the hospital who was not wearing PPE at the bedside of a confirmed case; full PPE was defined as correctly fitted high filtration mask (FFP3), gown, gloves and eye protection;
Other setting	A person who had prolonged (>15 min) face-to-face contact with a confirmed symptomatic case in any other enclosed setting.

Source: Adopted from Ref. [16].