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

Abstract

C oronavirus disease (COVID-19) was fi rst identifi ed in Wuhan, China, in December 2019 (1). The fi rst reported case in the United States was identifi ed 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 confi rmed COVID-19 cases in the United States (onset mid-January through early April 2020) and identifi ed 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 Offi ce of Management and Budget (no. 0920-1011).

Case–control study to identify risk factors for SARS‐CoV‐2 infection among university students in the northeastern USA

“…Evidence of transmission among students within shared university housing was also found in England, using a genomic epidemiologic approach (Aggarwal et al., 2022 ). Our findings are also consistent with the recognized role of household transmission in COVID‐19 epidemiology (Burke et al., 2021 ; Madewell et al., 2021 ). If feasible, reducing the number of students living in campus residence halls would help decrease the risk of SARS‐CoV‐2 transmission at universities.…”

Household Secondary Attack Rates of SARS-CoV-2 by Variant and Vaccination Status

“…We identified 2097 records (1791 from PubMed, 306 from medRxiv, and 2 from reference lists of eligible articles) published between June 18, 2021, and March 8, 2022 (eFigure 1 in the Supplement ). Fifty-eight new studies 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 (eTable 2 in the Supplement ) were combined with 77 studies from ou...…”

“…We identified 2097 records (1791 from PubMed, 306 from medRxiv, and 2 from reference lists of eligible articles) published between June 18, 2021, and March 8, 2022 (eFigure 1 in the Supplement). Fifty-eight new studies (eTable 2 in the Supplement) were combined with 77 studies from our previous review (see eTable 3 in the Supplement for references included from our previous review), with Figure 1 showing household SAR by study period, resulting in 135 total studies representing 1 375 806 contacts from 36 countries. Four of the new studies were preprints in our previous review that were subsequently published.…”

Missing science: A scoping study of COVID-19 epidemiological data in the United States

“…Analytic studies most applied cross-sectional (41/103), ecologic (25/103) or retrospective (23/103) designs. The most Nine analytic studies estimated the secondary attack rate [208,223,237,235,244,248,288,297,307]. Only one only of these estimated the SAR for non-household contacts [307].…”