Occupational risk of SARS-CoV-2 infection and reinfection during the second pandemic surge: a cohort study
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Abstract
This cohort study including essential workers, assessed the risk and incidence of SARS-CoV-2 infection during the second surge of COVID-19 according to baseline serostatus and occupational sector.
Methods
Essential workers were selected from a seroprevalence survey cohort in Geneva, Switzerland and were linked to a state centralised registry compiling SARS-CoV-2 infections. Primary outcome was the incidence of virologically confirmed infections from serological assessment (between May and September 2020) to 25 January 2021, according to baseline antibody status and stratified by three predefined occupational groups (occupations requiring sustained physical proximity, involving brief regular contact or others).
Results
10 457 essential workers were included (occupations requiring sustained physical proximity accounted for 3057 individuals, those involving regular brief contact, 3645 and 3755 workers were classified under ‘Other essential occupations’). After a follow-up period of over 27 weeks, 5 (0.6%) seropositive and 830 (8.5%) seronegative individuals had a positive SARS-CoV-2 test, with an incidence rate of 0.2 (95% CI 0.1 to 0.6) and 3.2 (95% CI 2.9 to 3.4) cases per person-week, respectively. Incidences were similar across occupational groups. Seropositive essential workers had a 93% reduction in the hazard (HR of 0.07, 95% CI 0.03 to 0.17) of having a positive test during the follow-up with no significant between-occupational group difference.
Conclusions
A 10-fold reduction in the hazard of being virologically tested positive was observed among anti-SARS-CoV-2 seropositive essential workers regardless of their sector of occupation, confirming the seroprotective effect of a previous SARS-CoV2 exposure at least 6 months after infection.
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SciScore for 10.1101/2021.08.06.21261419: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: Ethics: The investigation conforms the principles of the Declaration of Helsinki and was approved as an amendment by the local Ethical Committee (Commission Cantonale d’Éthique de la Recherche, Geneva, Switzerland; CCER 2020-00881).
Consent: All participants gave written informed consent at the time of recruitment.Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis 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 …SciScore for 10.1101/2021.08.06.21261419: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: Ethics: The investigation conforms the principles of the Declaration of Helsinki and was approved as an amendment by the local Ethical Committee (Commission Cantonale d’Éthique de la Recherche, Geneva, Switzerland; CCER 2020-00881).
Consent: All participants gave written informed consent at the time of recruitment.Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis 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:The study has some limitations. First, essential workers were categorized into three pre-specified groups, based on previous reports on exposure risk, though these groupings are imperfect and may not entirely reflect exposure.4 Second, our sample was composed by a significant proportion of cross-border workers, possibly being tested outside Geneva. Similar results, however, were observed when border workers were excluded (HR of 0.04, 95%CI 0.01 to 0.14). Third, participants of the SEROCoV-WORK+ were included on a voluntary basis, and selection towards participants better aware of sanitary measures might have occurred, potentially underestimating reinfection risk and limiting generalizability of results. Finally, we cannot infer cross-protection against new SARS-CoV-2 variants because they were underrepresented during the study period. This study has several important strengths. First, serological status assessment occurred in the early phases of the pandemic allowing a longitudinal follow-up covering the second pandemic surge. Second, this study took place before vaccination era, consenting us to properly evaluate the protective effect conferred by natural infection. Third, a large number of essential occupations were represented, providing information outside the healthcare sector. Finally, study results were concordant in all sensitivity analyses raising robustness of our observations. In conclusion, we observed no significant differences in documented SARS-CoV-2 infections...
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.
Results from scite Reference Check: We found no unreliable references.
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