Antibody status and cumulative incidence of SARS-CoV-2 infection among adults in three regions of France following the first lockdown and associated risk factors: a multicohort study.
Int J Epidemiol
; 50(5): 1458-1472, 2021 Nov 10.
Article
in English
| MEDLINE | ID: covidwho-1320316
ABSTRACT
BACKGROUND:
We aimed to estimate the seropositivity to anti-SARS-CoV-2 antibodies in May-June 2020 after the first lockdown period in adults living in three regions in France and to identify the associated risk factors.METHODS:
Between 4 May 2020 and 23 June 2020, 16 000 participants in a survey on COVID-19 from an existing consortium of three general adult population cohorts living in the Ile-de-France (IDF) or Grand Est (GE) (two regions with high rate of COVID-19) or in the Nouvelle-Aquitaine (NA) (with a low rate) were randomly selected to take a dried-blood spot for anti-SARS-CoV-2 antibodies assessment with three different serological methods (ClinicalTrial Identifier #NCT04392388). The primary outcome was a positive anti-SARS-CoV-2 ELISA IgG result against the spike protein of the virus (ELISA-S). Estimates were adjusted using sampling weights and post-stratification methods. Multiple imputation was used to infer the cumulative incidence of SARS-CoV-2 infection with adjustments for imperfect tests accuracies.RESULTS:
The analysis included 14 628 participants, 983 with a positive ELISA-S. The weighted estimates of seropositivity and cumulative incidence were 10.0% [95% confidence interval (CI) 9.1%, 10.9%] and 11.4% (95% CI 10.1%, 12.8%) in IDF, 9.0% (95% CI 7.7%, 10.2%) and 9.8% (95% CI 8.1%, 11.8%) in GE and 3.1% (95% CI 2.4%, 3.7%) and 2.9% (95% CI 2.1%, 3.8%) in NA, respectively. Seropositivity was higher in younger participants [odds ratio (OR) = 1.84 (95% CI 1.79, 6.09) in <40 vs 50-60 years old and OR = 0.56 (95% CI 0.42, 0.74) in ≥70 vs 50-60 years old)] and when at least one child or adolescent lived in the same household [OR = 1.30 (95% CI 1.11, 1.53)] and was lower in smokers compared with non-smokers [OR = 0.71 (95% CI 0.57, 0.89)].CONCLUSIONS:
Seropositivity to anti-SARS-CoV-2 antibodies in the French adult population was ≤10% after the first wave. Modifiable and non-modifiable risk factors were identified.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
SARS-CoV-2
/
COVID-19
Type of study:
Cohort study
/
Experimental Studies
/
Observational study
/
Prognostic study
/
Randomized controlled trials
Limits:
Adolescent
/
Adult
/
Child
/
Humans
/
Middle aged
Country/Region as subject:
Europa
Language:
English
Journal:
Int J Epidemiol
Year:
2021
Document Type:
Article
Affiliation country:
Ije
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