Persistence of SARS-CoV-2 antibodies and symptoms in an Irish Healthcare Worker (HCW) setting: Results of the COVID Antibody Staff Testing (CAST) Study

  1. Joanna Griffin
  2. Elizabeth Tully
  3. Fiona Cody
  4. Katherine Edwards
  5. Kara Moran
  6. David LeBlanc
  7. John O’Loughlin
  8. Ruth McLoughlin
  9. Rachel Cummins
  10. Sheila Breen
  11. Richard Drew
  12. Dominick Natin
  13. Fergal Malone

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Abstract

Objectives

This study examined the natural history, including incidence and prevalence, of SARS-CoV-2 antibodies serially up to 6 months post infection in Irish Healthcare Workers (HCWs) at an academic tertiary maternity hospital, during the first pandemic peak from March to September 2020.

Design

This single centre observational study profiled SARS-CoV-2 incidence and infection using viral RNA detected using oro/nasopharyngeal swabs accompanied by serological assessment of study participants for the presence of S SARS-CoV-2 antibodies. Participant demographics were also collected alongside information on clinical symptoms and time to recovery. Real time polymerase-chain-reaction (RT-PCR) for viral RNA SARS-CoV-2 detection was performed using the Allplex™ SARS-CoV-2 three gene target 2019-nCoV assay (SeeGene Inc., Rep. of Korea) or the Xpert Xpress SARS-CoV-2 assay on the GeneXpert platform (Cepheid, USA). Blood samples were obtained at the time of initial swab and at up to 4 time points thereafter, for the serological assessment of antibodies against both the spike and nucleocapsid protein antigens of SARS-CoV-2. Serological response was measured using the Captia™ Anti-SARS-CoV-2 (IgG) ELISA (Trinity Biotech) as part of a clinical performance evaluation. Two other testing methods were also used; the Anti-SARS-CoV-2 ELISA (IgG) assay (EuroImmun) and the Abbott Anti-SARS-CoV-2 IgG 75 kit on the Architect™ i2000SR instrument (Abbott Laboratories).

Setting

Academic Tertiary Maternity Hospital in Dublin, Ireland.

Participants

We invited symptomatic and asymptomatic healthcare workers employed at the Rotunda Maternity Hospital to participate in the CAST study.

Main Outcome Measures

The CAST study aimed to examine incidence and clinical symptoms of SARS-CoV-2 in HCWs and to determine the presence and longevity of antibodies in this group. We also sought to examine the clinical utility of the Captia™ Anti-SARS-CoV-2 (IgG) ELISA (Trinity Biotech) and to compare it to the current “accepted” gold standard platform in Ireland.

Results

By July 2020, 398 molecular tests had been completed on symptomatic staff with clinical suspicion of SARS-CoV-2 infection. In this cohort, 14% (n=54/398) had SARS-CoV-2 RNA detected by RT-PCR. The CAST study enrolled 137 HCWs with 86 participants symptomatic at time of swab collection and a further 51 asymptomatic control participants. SARS-CoV-2 RNA was detected in 52% (n=45/86) symptomatic study participants and serological positivity was confirmed in 98% (n=44/45) of those participants. Asymptomatic SARS-CoV-2 RNA infection was detected in 4% (n=2/51) of control participants with a seropositivity rate in this group of 8% (n=4/51). We demonstrated that 95% of SARS-CoV-2 PCR positive participants have detectable levels of antibodies at 100 days post infection, which persisted in 91% of participants at day 160+. Ongoing symptoms up to six months post infection were present in 50% of study participants with positive PCR and serology results. These data will be important to consider for long-term workforce planning in a healthcare setting, as the ongoing pandemic continues.

Funding

The CAST study was supported by the Rotunda Hospital and Trinity Biotech.

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  1. ScreenIT

    SciScore for 10.1101/2021.02.10.20248323: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: The study was approved by the Hospital Research Ethics Committee (REC-2020-012).
    Consent: Participants provided written informed consent for collection of both oro/nasopharyngeal swabs and serum samples.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    The anti-SARS-CoV-2 ELISA (IgG) requires a sample volume of 10μL for the detection of IgG antibody to SARS-CoV-2 (10μL diluted with 1mL of sample diluent).
    anti-SARS-CoV-2 ELISA (IgG
    suggested: None
    SARS-CoV-2
    suggested: None
    Software and Algorithms
    SentencesResources
    In addition, serum samples from all 137 study participants were tested on the Abbott Architect™ i2000SR instrument using the Abbott SARS-CoV-2 IgG75 assay following the manufacturer’s instructions.
    Abbott Architect™
    suggested: (Abbott ARCHITECT i1000sr System, RRID:SCR_019328)
    Abbott
    suggested: (Abbott, RRID:SCR_010477)

    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:
    However, the limitation of closed platform systems from a single supplier is around supply of reagents, analogous to the problems with reagents for PCR testing.27 The clinical performance of the Trinity Biotech Captia™ SARS-CoV-2-IgG kit in a healthcare worker population was evaluated as part of the CAST study. The Positive Percent Agreement (or estimated sensitivity) and the Negative Percent Agreement (or estimated specificity) were 95.92% and 100% respectively at >14 days post swab, providing a reliable and robust methodology for determining IgG levels in healthcare workers with impactful utility in the medium to long term management of the COVID-19 pandemic. There has been much discussion regarding antibody levels and their potential associated protection against SARS-CoV-2 re-infection. A study on SARS, a similar coronavirus to SARS-CoV-2, showed recovered individuals maintained neutralising antibodies for two years on average.28 In addition, antibody responses in individuals with laboratory-confirmed MERS-CoV infection lasted for at least 34 months after the outbreak.29 Long et al. and more recently Ward et al. have suggested a rapid decay of anti-SARS-CoV-2 IgG, although our findings do not support this assertion.30,31 Ward’s seroprevalence study on a large population in the U.K using lateral flow immunoassay testing found that healthcare workers along with ethnic minorities and care home workers were disproportionately affected by the pandemic with more positive test r...

    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 10.1101/2021.02.10.20248323v1 on medRxiv