Marcella Broccia1,2, Victoria Elizabeth de Knegt3, Elisabeth Helen Anna Mills4, Amalie Lykkemark Møller2, Filip Gnesin2, Thea K Fischer5, Nertila Zylyftari2, Stig Nikolaj Blomberg6, Mikkel Porsborg Andersen2, Morten Schou7, Emil Fosbøl8, Kristian Kragholm7,9, Helle Collatz Christensen10, Laura Bech Polcwiartek11, Matthew Phelps12, Lars Køber9, Christian Torp-Pedersen2,4. 1. Department of Obstetrics and Gynaecology, Aalborg University Hospital, Reberbansgade, Aalborg, Denmark. 2. Department of Cardiology, Nordsjællands Hospital, Dyrehavevej, Hillerød, Denmark. 3. Department of Pediatrics, Hvidovre Hospital, Kettegård alle, Hvidovre, Denmark. 4. Department of Cardiology, Aalborg University Hospital, Hobrovej, Aalborg, Denmark. 5. Department of Clinical Research, Nordsjællands Hospital, Dyrehavevej, Hillerød, Denmark. 6. Emergency Medical Services, University of Copenhagen, Region Hovedstaden (Capital Region of Denmark). 7. Department of Cardiology, Herlev Gentofte Hospital, Hospitalsvej, Hellerup, Denmark. 8. Department of Cardiology, Rigshospitalet, Blegdamsvej, København Ø, Denmark. 9. Unit of Clinical Biostatistics and Epidemiology, Aalborg University Hospital, Reberbansgade, Aalborg, Denmark. 10. Danish Clinical Quality Program (RKKP), National Clinical Registries, Frederiksberg Hospital, Denmark. 11. Department of Pediatrics, Aalborg University Hospital, Reberbansgade, Aalborg, Denmark. 12. The Danish Heart Foundation, Copenhagen, Denmark.
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.
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.