SARS-CoV-2 transmission from the healthcare setting into the home: a prospective longitudinal cohort study

  1. Simon Craxford
  2. Jessica Nightingale
  3. Adeel Ikram
  4. Ben Arthur Marson
  5. Anthony Kelly
  6. Alan Norrish
  7. Amrita Vijay
  8. Stuart Astbury
  9. Lola Cusin
  10. Waheed Ashraf
  11. Jayne Newham
  12. Guruprasad Aithal
  13. Patrick Tighe
  14. Jonathan Ball
  15. Alexander W Tarr
  16. Richard A Urbanowicz
  17. Ana Valdes
  18. Benjamin Ollivere

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Abstract

Objective To assess the incidence of symptomatic and asymptomatic SARS-CoV-2 seropositivity in healthcare workers and subsequent transmission to their close contacts within their household. To assess changes in immunoglobulin (Ig) and neutralising antibodies (nAbs) in exposed participants. Setting Two acute National Health Service (NHS) hospitals within the East Midlands region of England. Background The UK has been one of the most severely affected countries during the COVID-19 pandemic. Transmission from healthcare workers to the wider community is a potential major vector for spread of SARS-CoV-2 which is not well described in the current literature. Methods Healthcare workers (HCW) were recruited from two Hospitals within the East Midlands of England and underwent serial blood sampling for anti-SARS-CoV-2 antibodies (both nucleocapsid and spike protein for IgG, IgM and IgA) between 20 April and 30 July 2020, with the presence of neutralising antibodies (nAbs) assessed for positive participants. Cohabitees of the volunteers were invited to attend testing in July -August 2020 and underwent identical serological testing as the HCWs. Results 633 healthcare professionals were recruited. 178 household contacts of 137 professionals volunteered for the study. 18% of healthcare professionals (115 out of 633) tested as seropositive during the study period, compared to an estimated seroprevalence of 7% within the general population. The rate of symptomatic COVID-19 was 27.5% compared to an asymptomatic rate of 15.1%. Rates of positivity declined across the study period for all immunoglobulins (overall positivity from 16.7% to 6.9%). 7.2% of the cohabitees tested as seropositive. 58 cohabitees lived with a serologically positive HCW; this group had a seropositive rate of 15.5%, compared to 2.5% of cohabitees without a seropositive HCW, a six-fold increase in risk (Odds ratio 7.16 95% CI 1.86 to 27.59), p = 0.0025). Given the observed decay rates and data from Public Health England, we estimate that the proportion of seropositive cohabitees living with a seropositive HCW at the height of the first wave could have been as high as 44%. 110 out of 115 (95.7%) HCWs and 12 out of 13 (92.3%) cohabitees who tested positive developed detectable nAbs. 56.5% (65 out of 115) of SARS-CoV-2 positive HCWs developed a neutralising titre with an IC50 1/300 dilution; no cohabitee achieved this level. Conclusions Transmission of SARS-CoV-2 between healthcare professionals and their home contacts appears to be a significant factor of viral transmission, but, even accounting for the decline in seropositivity over time, less than 44% of adult cohabitees of seropositive healthcare workers became seropositive. Routine screening and priority vaccination of both healthcare professionals and their close contacts should be implemented to reduce viral transmission from hospitals to the community.

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  1. ScreenIT

    SciScore for 10.1101/2021.02.01.21250950: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementConsent: All participants provided written informed consent prior to completing the questionnaire and providing blood samples.
    IRB: The study protocol was approved by North West - Greater Manchester South Research Ethics Committee (reference 20/NW/0395).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    The PANTHER protocol is available online (www.pantherstudy.org.uk).
    PANTHER
    suggested: (PANTHER, RRID:SCR_004869)
    Statistical analysis was performed using IBM SPSS Version 24
    SPSS
    suggested: (SPSS, RRID:SCR_002865)
    Figures were produced using Graphpad Prism version 8.
    Graphpad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    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:
    Limitations: There are limitations to this study. A major drawback in terms of assessing the factors affecting transmission is the number of seropositive cohabitees, i.e., putative transmission events. Although we found a considerably larger proportion (55.6%) of symptomatic seropositive HCW has seropositive cohabitees than those who had seronegative cohabitees (37.5%) there are only n=9 pairs where both the HCW and cohabitee were seropositive. This highlights the need for larger HCW-cohabitee pair studies to investigate the risks of transmission. In addition, no single assay has perfect sensitivity and specificity30. Few participants had tested positive on nasal SARS-CoV-2 PCR. Routine screening of staff members was not in force during the study period so our results could not be compared to swab or other independently collected results. Our cohort was largely asymptomatic or had low-level symptoms; further study is needed to confirm the generalisability of our results to patients with more severe cases of COVID-19. The cohabitee cohort also only donated a single sample. We were therefore unable to confirm the direction of SARS-CoV-2 transmission as it is possible that the positive cohabitees actually transmitted the virus to the HCW. This raises an additional risk of viral spread, as healthcare workers infected by their cohabitees may transmit the virus into “green” COVID-19 free areas of the hospital. In addition, as the single blood sample was taken later in the study for...

    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.

  2. Version published to 10.1101/2021.02.01.21250950v1 on medRxiv