SARS-CoV-2 infection in households with and without young children: Nationwide cohort study, Denmark, 27 February 2020 to 26 February 2021

  1. Anders Husby
  2. Giulia Corn
  3. Tyra Grove Krause

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Abstract

Infections with seasonally spreading coronaviruses are common among young children during winter months in the northern hemisphere; the immunological response lasts around a year. However, it is not clear if living with young children changes the risk of SARS-CoV-2 infection among adults.

Aim

Our aim was to investigate the association between living in a household with younger children and the risk of SARS-CoV-2 infections and hospitalisation.

Methods

In a nationwide cohort study, we followed all adults in Denmark aged 18 to 60 years from 27 February 2020 to 26 February 2021. Hazard ratios of SARS-CoV-2 infection by number of 10 months to 5 year-old children in the household were estimated using Cox regression adjusted for adult age, sex and other potential confounders. In a sensitivity analysis, we investigated the effect of the children's age.

Results

Among 450,007 adults living in households with young children, 19,555 were tested positive for SARS-CoV-2, while among 2,628,500 adults without young children in their household, 110,069 were tested positive for SARS-CoV-2 (adjusted hazard ratio (aHR) = 1.10; 95% confidence interval (CI): 1.08–1.12). Among adults with young children, 620 were hospitalised with SARS-CoV-2, while 4,002 adults without children were hospitalised with SARS-CoV-2 (aHR = 0.97; 95% CI: 0.88–1.08). Sensitivity analyses found that an increasing number of younger children substantially increased the risk of SARS-CoV-2 infection but not hospitalisation.

Conclusion

Living in a household with young children was associated with a small increased risk of SARS-CoV-2 infection.

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  1. Version published to 10.2807/1560-7917.es.2022.27.32.2101096
  2. ScreenIT

    SciScore for 10.1101/2021.02.28.21250921: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Our study has some limitations. We did not have serological measurements of B-cell or T-cell immunity to HCoVs, which could offer direct biological evidence of preexisting immunity against SARS-CoV-2 following prior exposure to HCoVs, but co-habitation with young children has been considered a reasonable proxy for recent exposure to HCoVs previously(7). Furthermore, we did not include information on SARS-CoV-2 testing of young children. However, young children are often asymptomatic or present with mild symptoms of infection(21), thus inclusion of this information would introduce undesirable health-seeking behavior bias into our analyses. Our findings show that having young children in one’s household was associated with a slightly increased risk of SARS-CoV-2 infection. The association could be a result of a higher number of social contacts among adults living in households with young children (e.g. more adults in the household, contact to daycare facilities, or close contact to parents of playmates) or due to infection brought into the household by the young children. Nevertheless, when we stratified by number of adults in the household we found no indication that an increased number of adults in the household was the driving force behind increased risk of SARS-CoV-2 infection. However, we found a heterogeneous pattern according to which the lowest relative risk of infection was in households with two adults, indicating that social circumstances, and not the household numbe...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2021.02.28.21250921v1 on medRxiv