Seroprevalence of anti-SARS-CoV-2 IgG antibodies, risk factors for infection and associated symptoms in Geneva, Switzerland: a population-based study
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Abstract
Aims: To assess SARS-CoV-2 seroprevalence over the first epidemic wave in the canton of Geneva, Switzerland, as well as risk factors for infection and symptoms associated with IgG seropositivity. Methods: Between April and June 2020, former participants of a representative survey of the 20–74-year-old population of canton Geneva were invited to participate in the study, along with household members aged over 5 years. Blood samples were tested for anti-SARS-CoV-2 immunoglobulin G. Questionnaires were self-administered. We estimated seroprevalence with a Bayesian model accounting for test performance and sampling design. Results: We included 8344 participants, with an overall adjusted seroprevalence of 7.8% (95% credible interval 6.8–8.9). Seroprevalence was highest among 18–49 year-olds (9.5%), and lowest in 5–9-year-old children (4.3%) and individuals >65 years (4.7-5.4%). Odds of seropositivity were significantly reduced for female retirees and unemployed men compared to employed individuals, and smokers compared to non-smokers. We found no significant association between occupation, level of education, neighborhood income and the risk of being seropositive. The symptom most strongly associated with seropositivity was anosmia/dysgeusia. Conclusions: Anti-SARS-CoV-2 population seroprevalence remained low after the first wave in Geneva. Socioeconomic factors were not associated with seropositivity in this sample. The elderly, young children and smokers were less frequently seropositive, although it is not clear how biology and behaviours shape these differences.
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SciScore for 10.1101/2020.12.16.20248180: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement Consent: Of note, during the study period, the country was initially under lockdown, then, measures were progressively relaxed in three consecutive periods.(20) Participants provided written informed consent to participate in the study, and parents or legal guardians gave consent for children under 18 years.
IRB: The study protocol was approved by the Cantonal Research Ethics Commission of Geneva, Switzerland (CER16-363) and is available online at https://static1.squarespace.com/static/5e7dd8f02d3bc353fbb05121/t/5e887016c7fa18312c3e00fa/1585999900784/Protocole_SEROCOV-POP30.03.pdf.Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as … SciScore for 10.1101/2020.12.16.20248180: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement Consent: Of note, during the study period, the country was initially under lockdown, then, measures were progressively relaxed in three consecutive periods.(20) Participants provided written informed consent to participate in the study, and parents or legal guardians gave consent for children under 18 years.
IRB: The study protocol was approved by the Cantonal Research Ethics Commission of Geneva, Switzerland (CER16-363) and is available online at https://static1.squarespace.com/static/5e7dd8f02d3bc353fbb05121/t/5e887016c7fa18312c3e00fa/1585999900784/Protocole_SEROCOV-POP30.03.pdf.Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not 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:Our study comes with a number of limitations. The Bus Santé source population was originally composed of individuals between 20 and 75 years old, explaining the lower number of participants aged less than 18 and over 75 years in our final sample, despite the inclusion of primary participants’ household members. Delayed recruitment by ordinary mail of participants without an email address on file is likely to have had an influence on weekly seroprevalence results. Further, the association of income level with a seropositive status could not be assessed exactly, as we did not collect individual participants’ income, but estimated income based on the place of residency. Memory bias has likely influenced symptoms analysis,as participants were asked to report symptoms having occurred up to six months earlier. Second, symptoms reported by IgG-positive participants might have been caused by other pathogens as 1644 participants reported multiple episodes. Finally, the severity of the disease was not addressed in this study. Our study determined that the average seroprevalence of SARS-CoV-2 in the canton of Geneva over the course of the first wave was 7.8 %, leaving most of the population naïve to the virus.(35) Our risk factor analysis indicates that while some socio-economic disparities in susceptibility to the infection do exist, they are likely more complex than what we previously thought. Older individuals seemed to be protected from infection during the first wave, perhaps due t...
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.
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