Seroprevalence of anti-SARS-CoV-2 antibodies after the first wave of the COVID-19 pandemic in a vulnerable population in France: a cross-sectional study

  1. Adeline Beaumont
  2. Cécile Durand
  3. Martine Ledrans
  4. Valérie Schwoebel
  5. Harold Noel
  6. Yann Le Strat
  7. Donatien Diulius
  8. Léa Colombain
  9. Marie Médus
  10. Philippe Gueudet
  11. Damien Mouly
  12. Hugues Aumaître

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Abstract

We aimed to assess the level of prior SARS-CoV-2 infection in socially deprived neighbourhoods after the first wave of the pandemic, and to identify factors associated with seropositivity.

Design

A cross-sectional study.

Setting

Three socially deprived neighbourhoods of the city of Perpignan, in the south of France, where large settled Roma communities live.

Participants

People aged 6 years old or over, living in the study area. 700 people were included in the study using two-stage stratified sampling design.

Interventions

The study included a questionnaire and SARS-CoV-2 antibody testing by the Roche Elecsys immunoassay between 29 June and 17 July 2020.

Primary and secondary outcome measures

SARS-CoV-2 antibody seroprevalence was estimated from weighted data. Associated factors and reported symptoms were investigated using univariable and multivariable logistic regressions.

Results

The seroprevalence of anti-SARS-CoV-2 antibodies was 35.4% (95% CI 30.2% to 41.0%). People aged 15–64 years old had increased odds of being seropositive than those aged 65 years or over. Obese people had higher odds of being seropositive (adjusted OR (aOR)=2.0, 95% CI 1.1 to 3.8). The odds of being seropositive were higher in households with clinical COVID-19 cases (one case: aOR=2.5, 95% CI 1.3 to 5.0; several cases: aOR=6.9, 95% CI 3.1 to 15.2). In the neighbourhood with the highest measured seroprevalence, people living in a dwelling with one to two rooms had higher odds of being seropositive than those living in a four-room house (aOR=2.8, 95% CI 1.2 to 6.3). Working during the lockdown was associated with lower odds of being seropositive (aOR=0.2, 95% CI 0.03 to 1.0).

Conclusion

Transmission of SARS-COV-2 in this vulnerable population was very high during the COVID-19 pandemic’s first wave. Our results highlight the need to strengthen and adapt preventive measures taking into account all social determinants of health, especially housing conditions.

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  1. Version published to 10.1136/bmjopen-2021-053201
  2. ScreenIT

    SciScore for 10.1101/2021.03.05.21252835: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: The study protocol was approved by a French ethics committee (Comité de Protection des Personnes Sud Est II, Lyon, 2020-A01828-31).
    Consent: All gave their prior oral consent to participate.
    RandomizationDepending on the household size, from one to four participants were then randomly recruited from households which agreed to participate (see: Supplemental materials - Survey procedure and logistics).
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Serological tests were performed using EIecsys Anti-SARS-CoV-213, an immunoassay for in vitro qualitative detection of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against the SARS-CoV-2 spike (S) protein in serum.
    Anti-SARS-CoV-213
    suggested: None
    immunoglobulin G (IgG
    suggested: None
    A person was defined seropositive if anti-SARS-CoV-2 antibodies (IgM or IgG) were detected by the immunoassay.
    anti-SARS-CoV-2
    suggested: None
    IgM
    suggested: None
    Software and Algorithms
    SentencesResources
    Study design and participants: SCoPe is a cross-sectional seroprevalence survey of a sample of the population living in three neighbourhoods (Saint-Jacques (neighbourhood A), Haut-Vernet (neighbourhood B) and Nouveau Logis (neighbourhood C)) in the city of Perpignan (Figure 1).
    SCoPe
    suggested: (Scope, RRID:SCR_017454)
    Data were analysed using Stata V14.2 software (StataCorp, College Station, TX, USA).
    StataCorp
    suggested: (Stata, RRID:SCR_012763)

    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 several limitations. First, it was conducted 4 months after the first wave ended, leading to possible recall bias in the reporting of symptoms. The assessment of behaviours during lockdown was very complex because of the fact that their evolution was not measured during the course of the first wave. It is important to underline that a qualitative study observed a shift in the three neighbourhoods’ awareness of the dangers of COVID-19 following the first deaths, particularly that of a young woman. The same study observed a substantial improvement in compliance with prevention measures during the lockdown19. This is why the association between these behaviours and seropositivity (except for going out to work) was not studied in our analysis. Second, the systematic sampling method used to select households made it difficult to estimate the total number of individuals to approach. Third, we also had difficulties reaching some of the selected households, despite flyers being placed in letterboxes and several visits. Finally, selection bias may have occurred. More specifically, people with a history of COVID-19 type symptoms may have been more willing to participate in the study than people with no such history. It is also possible that people who had been tested positive before the study were less willing to participate. Incomplete data on reasons for non-response prevented us from further exploring this issue. The high estimated seroprevalence after the first wave o...

    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 10.1101/2021.03.05.21252835v1 on medRxiv