Patterns of Virus Exposure and Presumed Household Transmission among Persons With Coronavirus Disease, United States, January–April 2020

Rachel M. Burke; Laura Calderwood; Marie E. Killerby; Candace E. Ashworth; Abby L. Berns; Skyler Brennan; Jonathan M. Bressler; Laurel Harduar Morano; Nathaniel M. Lewis; Tiff anie M. Markus; Suzanne M. Newton; Jennifer S. Read; Tamara Rissman; Joanne Taylor; Jacqueline E. Tate; Claire M. Midgley


Emerging Infectious Diseases. 2021;27(9):2323-2332. 

In This Article

Abstract and Introduction


We characterized common exposures reported by a convenience sample of 202 US patients with coronavirus disease during January–April 2020 and identified factors associated with presumed household transmission. The most commonly reported settings of known exposure were households and healthcare facilities; among case-patients who had known contact with a confirmed case-patient compared with those who did not, healthcare occupations were more common. Among case-patients without known contact, use of public transportation was more common. Within the household, presumed transmission was highest from older (≥65 years) index case-patients and from children to parents, independent of index case-patient age. These findings may inform guidance for limiting transmission and emphasize the value of testing to identify community-acquired infections.


Coronavirus disease (COVID-19) was first identified in Wuhan, China, in December 2019.[1] The first reported case in the United States was identified in January 2020;[2] by mid-March, cases had been reported in all 50 states.[3] On March 16, 2020, the White House Coronavirus Task Force published guidance for curbing community spread of COVID-19;[4] soon after, states began to enact stay-at-home orders.[5] By late May 2020, all 50 states had begun easing restrictions; reported cases reached new peaks in the summer and then winter months of 2020.[6,7] As restrictions further ease with increased availability of vaccine, and as pandemic fatigue may cause persons to adhere less consistently to recommended guidance such as masking and distancing, it may be informative to look back at exposures and within-household transmission during a period when few mitigation measures were in place. We characterized exposures common among persons with the earliest reported confirmed COVID-19 cases in the United States (onset mid-January through early April 2020) and identified factors associated with presumed household transmission.

This activity was reviewed by the Centers for Disease Control and Prevention (CDC) and was conducted consistent with applicable federal law and CDC policy. Forms were approved under the Office of Management and Budget (no. 0920–1011).