Seroprevalence of SARS-CoV-2 IgG Antibodies in Corsica (France), April and June 2020

  1. Lisandru Capai
  2. Nazli Ayhan
  3. Shirley Masse
  4. Jean Canarelli
  5. Stéphane Priet
  6. Marie-Hélène Simeoni
  7. Remi Charrel
  8. Xavier de Lamballerie
  9. Alessandra Falchi

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Abstract

Our aim was to assess the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection after the lockdown in a sample of the Corsican population. Between 16 April and 15 June 2020, 2312 residual sera were collected from patients with a blood analysis conducted in one of the participating laboratories. Residual sera obtained from persons of all ages were tested for the presence of anti-SARS-CoV-2 Immunoglobulin G (IgG) using the EUROIMMUN enzyme immunoassay kit for semiquantitative detection of IgG antibodies against the S1 domain of viral spike protein (ELISA-S). Borderline and positive samples in ELISA-S were also tested with an in-house virus neutralization test (VNT). Prevalence values were adjusted for sex and age. A total of 1973 residual sera samples were included in the study. The overall seroprevalence based on ELISA-S was 5.27% (95% confidence interval (CI), 4.33–6.35) and 5.46% (4.51–6.57) after adjustment. Sex was not associated with IgG detection. However, significant differences were observed between age groups (p-value = 1 E-5). The highest values were observed among 10–19, 30–39, and 40–49 year-old age groups, ranging around 8–10%. The prevalence of neutralizing antibody titers ≥40 was 3% (2.28–3.84). In conclusion, the present study showed a low seroprevalence for COVID-19 in Corsica, a finding that is in accordance with values reported for other French regions in which the impact of the pandemic was low.

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  1. Version published to 10.3390/jcm9113569
  2. ScreenIT

    SciScore for 10.1101/2020.09.29.20201368: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    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: We detected the following sentences addressing limitations in the study:
    There are several limitations in our study. Firstly, residual sera from screening or routine care provided by private medical biology laboratories, are more likely to come from people needing to monitor their health status for chronic medical conditions. Thus data cannot be extrapolated to the general population although we have adjusted the data according to the age and sex of the general Corsican population. Additionally, no data concerning clinical features, chronic disease, or possible COVID-19 exposures were available potentially biasing results. Moreover, this lack of information on the COVID-19 status of the persons included could also influence the specificity and sensitivity of the ELISA test (timing of the sample in relation to the infection). As we tested by seroneutralization samples with an ELISA-S test optical density ≥0.8 and not all samples, seoprevalence could be slightly underestimated. The strengths of this study were the size of the sample and its representativity in terms of age and gender. Samples have been analysed by combining ELISA and neutralization methods to strengthen results. In conclusion the present study showed that a low seroprevalence for COVID-19 in Corsica in accordance with values reported for other French regions in which the impact of the pandemic was low. This regional study is particularly important in Corsica, as the island situation cannot be extrapolated from neighboring regions.

    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

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  3. Version published to 10.1101/2020.09.29.20201368v1 on medRxiv