Household Exposure to Severe Acute Respiratory Syndrome Coronavirus 2 and Association With Coronavirus Disease 2019 Severity: A Danish Nationwide Cohort Study

Marcella Broccia, Victoria Elizabeth de Knegt, Elisabeth Helen Anna Mills, Amalie Lykkemark Møller, Filip Gnesin, Thea K. Fischer, Nertila Zylyftari, Stig Nikolaj Blomberg, Mikkel Porsborg Andersen, Morten Schou, Emil Fosbøl, Kristian Kragholm, Helle Collatz Christensen, Laura Bech Polcwiartek, Matthew Phelps, Lars Køber, Christian Torp-Pedersen

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Abstract

BACKGROUND: Households are high-risk settings for the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Severity of coronavirus disease 2019 (COVID-19) is likely associated with the infectious dose of SARS-CoV-2 exposure. We therefore aimed to assess the association between SARS-CoV-2 exposure within households and COVID-19 severity. METHODS: We performed a Danish, nationwide, register-based, cohort study including laboratory-confirmed SARS-CoV-2-infected individuals from 22 February 2020 to 6 October 2020. Household exposure to SARS-CoV-2 was defined as having 1 individual test positive for SARS-CoV-2 within the household. Cox proportional hazards models were used to estimate the association between "critical COVID-19" within and between households with and without secondary cases. RESULTS: From 15 063 multiperson households, 19 773 SARS-CoV-2-positive individuals were included; 11 632 were categorized as index cases without any secondary household cases; 3431 as index cases with secondary cases, that is, 22.8% of multiperson households; and 4710 as secondary cases. Critical COVID-19 occurred in 2.9% of index cases living with no secondary cases, 4.9% of index cases with secondary cases, and 1.3% of secondary cases. The adjusted hazard ratio for critical COVID-19 among index cases vs secondary cases within the same household was 2.50 (95% confidence interval [CI], 1.88-3.34), 2.27 (95% CI, 1.77-2.93) for index cases in households with no secondary cases vs secondary cases, and 1.1 (95% CI, .93-1.30) for index cases with secondary cases vs index cases without secondary cases. CONCLUSIONS: We found no increased hazard ratio of critical COVID-19 among household members of infected SARS-CoV-2 index cases.

Original languageEnglish
JournalClinical infectious diseases : an official publication of the Infectious Diseases Society of America
Volume74
Issue number1
Pages (from-to)1-7
Number of pages7
ISSN1058-4838
DOIs
Publication statusPublished - 2022

Bibliographical note

Publisher Copyright:
© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: [email protected].

Keywords

  • corona
  • death
  • infectious dose
  • transmission
  • viral load

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