A Multidimensional Cross-Sectional Analysis of Coronavirus Disease 2019 Seroprevalence Among a Police Officer Cohort: The PoliCOV-19 Study

  1. Parham Sendi
  2. Rossella Baldan
  3. Marc Thierstein
  4. Nadja Widmer
  5. Peter Gowland
  6. Brigitta Gahl
  7. Annina Elisabeth Büchi
  8. Dominik Güntensperger
  9. Manon Wider
  10. Manuel Raphael Blum
  11. Caroline Tinguely
  12. Cédric Maillat
  13. Elitza S Theel
  14. Elie Berbari
  15. Ronald Dijkman
  16. Christoph Niederhauser

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Abstract

Background

Protests and police fieldwork provide a high-exposure environment for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. In this cross-sectional analysis, we investigated the seroprevalence among a police cohort, and sociodemographic, work, and health-related factors associated with seropositivity.

Methods

Study participants were invited for serological testing of SARS-CoV-2 and to complete online questionnaires. Serum neutralization titers toward the wild-type SARS-CoV-2 spike protein (expressing D614G) and the Alpha and Beta variants were measured in seropositive study participants.

Results

A total of 978 police personnel representing 35% of the entire staff participated from February to March 2021. The seroprevalence was 12.9%. It varied by geographic region, ranged from 9% to 13.5% in 3 regions, including the city; and was 22% in Bernese Seeland/Jura with higher odds for seropositivity (odds ratio [OR], 2.38 [95% confidence interval {CI}, 1.28–4.44], P=.006). Job roles with mainly office activity were associated with a lower risk of seropositivity (OR, 0.33 [95% CI, .14–.77], P=.010). Self-reported compliance with mask wearing during working hours was 100%; 45% of seropositive vs 5% of seronegative participants (P<.001) reported having had contact with a proven coronavirus disease 2019 (COVID-19) case living in the same household prior to serological testing. The level of serum antibody titers correlated with neutralization capacity. Antibodies derived from natural SARS-CoV-2 infection effectively neutralized the SARS-CoV-2 spike protein, but were less effective against the Alpha and Beta variants.

Conclusions

The seroprevalence of anti–SARS-CoV-2 antibodies of police officers was comparable to that reported in the general population, suggesting that the personal protective equipment of the police is effective, and that household contacts are the leading transmission venues. The level of serum antibody titers, in particular that of anti-spike antibodies, correlated well with neutralization capacity. Low antibody titers acquired from natural infection were not effective against variants.

Clinical Trials Registration

NCT04643444.

Article activity feed

  1. Version published to 10.1093/ofid/ofab524
  2. ScreenIT

    SciScore for 10.1101/2021.08.09.21261789: (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 AnalysisThe sample size calculation conducted prior to the study yielded a 95% confidence interval width of 4%, assuming a true seroprevalence of 12% to 13% and inclusion of 1,000 study participants.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Antibody tests: SARS-CoV-2 antibodies to the nucleocapsid protein (NCP) and spike (S) protein were measured by using two commercially available immunoassays: anti-SARS-CoV-2 and anti-SARS-CoV-2 S (Roche Diagnostics, Rotkreuz,
    anti-SARS-CoV-2
    suggested: None
    anti-SARS-CoV-2 S
    suggested: None
    Both immunoassays detect antibodies independent of isotype, detecting predominantly IgG antibodies, as well as IgA and IgM antibodies.
    IgM
    suggested: None
    The anti⍰SARS⍰CoV⍰2 assay is based on antibody detection to a recombinant SARS-CoV-2 NCP, whereas the anti-SARS-CoV-2 S uses a recombinant receptor binding domain antigen, which is found on subunit 1 of the S protein.
    anti⍰SARS⍰CoV⍰2
    suggested: None
    anti-SARS-CoV-2 S uses a recombinant receptor binding domain antigen ,
    suggested: None
    Among seronegative samples, only those from individuals who reported having had a positive test result from a nasopharyngeal swab in the online questionnaire were tested for anti-S antibodies (supplemental fig A)
    anti-S
    suggested: None
    We calculated separate analyses, including both anti-NCP and anti-S antibodies as covariates into the model as continuous variables or dichotomized by the median, respectively.
    anti-NCP
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    19 In brief, 20,000 Vero E6 cells were seeded in a 96-well plate format.
    Vero E6
    suggested: None

    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 limitations. The investigation was performed in February 2021 and we used anti-NCP antibodies as the main marker of seropositivity. We cannot exclude that in certain individuals with COVID-19 in 2020 anti-NCP antibodies have waned below the detection level and that the true seroprevalence is underestimated. In our experience, the antibody titres remain at a detectable level for a prolonged period, and the proportion of agreement with reported nasopharyngeal swab test results was high. Therefore, and in consideration of a 95% confidence interval width of 4%, we are convinced that the seroprevalence proportion found in our analysis is a valid result. We categorized our analysis only in anti-NCP seropositive and seronegative individuals and did not correct for sensitivity and specificity. It is therefore possible that we included very few false positive or false negative serum samples in our analysis. Given the high sensitivity and specificity of the antibody tests, we do not believe that excluding these few samples would have changed the overall results. The results from nasopharyngeal swab tests were obtained via online questionnaire, and the questionnaires on the subjective view of transmission routes may consist of a recall bias. The choice of median cut-off values of antibody titres in association with serum neutralization assays is arbitrary and does not reflect clinical circumstances. More sophisticated methods to find an optimal cut-off such as receiver ope...

    Results from TrialIdentifier: We found the following clinical trial numbers in your paper:

    IdentifierStatusTitle
    NCT04643444Enrolling by invitationPolice COVID-19 Serosurvey

    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.

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

    About SciScore

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  3. Version published to 10.1101/2021.08.09.21261789v1 on medRxiv