Relative contribution of leaving home for work or education, transport, shopping and other activities on risk of acquiring COVID-19 infection outside the household in the second wave of the pandemic in England and Wales

  1. S Hoskins
  2. S Beale
  3. RW Aldridge
  4. AMD Navaratnam
  5. C Smith
  6. CE French
  7. A Yavlinsky
  8. V Nguyen
  9. T Byrne
  10. J Kovar
  11. E Fragaszy
  12. WLA Fong
  13. C Geismar
  14. P Patel
  15. AM Johnson

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Abstract

Background

With the potential for and emergence of new COVID-19 variants, such as the reportedly more infectious Omicron, and their potential to escape the existing vaccines, understanding the relative importance of which non-household activities increase risk of acquisition of COVID-19 infection is vital to inform mitigation strategies.

Methods

Within an adult subset of the Virus Watch community cohort study, we sought to identify which non-household activities increased risk of acquisition of COVID-19 infection and which accounted for the greatest proportion of non-household acquired COVID-19 infections during the second wave of the pandemic. Among participants who were undertaking antibody tests and self-reporting PCR and lateral flow tests taken through the national testing programme, we identified those who were thought to be infected outside the household during the second wave of the pandemic. We used exposure data on attending work, using public or shared transport, using shops and other non-household activities taken from monthly surveys during the second wave of the pandemic. We used multivariable logistic regression models to assess the relative independent contribution of these exposures on risk of acquiring infection outside the household. We calculated Adjusted Population Attributable Fractions (APAF - the proportion of non-household transmission in the cohort thought to be attributable to each exposure) based on odds ratios and frequency of exposure in cases.

Results

Based on analysis of 10475 adult participants including 874 infections acquired outside the household, infection was independently associated with: leaving home for work (AOR 1.20 (1.02 – 1.42) p=0.0307, APAF 6.9%); public transport use (AOR for use more than once per week 1.82 (1.49 – 2.23) p<0.0001, APAF for public transport 12.42%); and shopping (AOR for shopping more than once per week 1.69 (1.29 – 2.21) P=0.0003, APAF for shopping 34.56%). Other non-household activities such as use of hospitality and leisure venues were rare due to restrictions and there were no significant associations with infection risk.

Conclusions

A high proportion of the second wave of the pandemic was spent under conditions where people were being advised to work from home where possible, and to minimize exposure to shops, and a wide range of other businesses were subject to severe restrictions. Vaccines were being rolled out to high-risk groups. During this time, going to work was an important risk factor for infection but public transport use likely accounted for a lot of this risk. Only a minority of the cohort left home for work or used public or shared transport. By contrast, the majority of participants visited shops and this activity accounted for about one-third of non-household transmission.

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  1. ScreenIT

    SciScore for 10.1101/2021.12.08.21267458: (What is this?)

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

    Table 1: Rigor

    Ethicsnot detected.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Cell Line AuthenticationAuthentication: A subset of the adult cohort have also undertaken antibody testing through venous blood draws since October 2020 and monthly finger-prick testing since March 2021.

    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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    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.
    • No funding statement was detected.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

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  2. Version published to 10.1101/2021.12.08.21267458v1 on medRxiv