Table 1. Contact definitions, number of contacts identified by category, and comments regarding the contact identification process during the contact investigation of an early confirmed US COVID-19 case, Washington, USA, 2020*.

Type

Definition†

Contacts

Comments

Community contact	Any close contact (being within 6 feet of the case-patient) for a prolonged time (>10 min), other than office co-worker	0	None
	Being an office co-worker of the case-patient with close contact of any duration	11 office co-workers	None
	Contact with infectious secretions from the case-patient	0	None
	Sharing a healthcare waiting room or area during the same time and up to 2 h after the case-patient was present	31 waiting room patients	7/31 of the waiting room contacts likely overlapped with the case-patient in the waiting room.
Healthcare contact	Any face-to-face interactions between an HCP and the case-patient without the HCP wearing full PPE†	6 HCP	None
	Potential contact with the case-patient’s infectious secretions by an HCP without wearing full PPE‡	2 HCP	2 HCP were EVS workers who did not have direct contact with the case-patient. They were included for potential exposure to infectious secretions from the case-patient while cleaning surfaces.

*COVID-19, coronavirus disease; EVS, environmental services; HCP, healthcare personnel; PPE, personal protective equipment.
†Contact definitions were developed on January 21, 2020, before published guidance from CDC for COVID-19 was available. Contacts were identified during the time from the case-patient’s symptom onset until the case-patient was appropriately isolated. An airport shuttle driver who had contact with the case-patient before symptom onset was identified during contact tracing but was not included in this investigation. He self-monitored for 14 days and reported remaining asymptomatic.
‡At the time of the investigation, full PPE consisted of gown, gloves, eye protection, and an N95 respirator.