Trends in social exposure to SARS-Cov-2 in France. Evidence from the national socio-epidemiological cohort–EPICOV

Abstract

Background We aimed to study whether social patterns of exposure to SARS-CoV-2 infection changed in France throughout the year 2020, in light to the easing of social contact restrictions. Methods A population-based cohort of individuals aged 15 years or over was randomly selected from the national tax register to collect socio-economic data, migration history, and living conditions in May and November 2020. Home self-sampling on dried blood was proposed to a 10% random subsample in May and to all in November. A positive anti-SARS-CoV-2 ELISA IgG result against the virus spike protein (ELISA-S) was the primary outcome. The design, including sampling and post-stratification weights, was taken into account in univariate and multivariate analyses. Results Of the 134,391 participants in May, 107,759 completed the second questionnaire in November, and respectively 12,114 and 63,524 were tested. The national ELISA-S seroprevalence was 4.5% [95%CI: 4.0%-5.1%] in May and 6.2% [5.9%-6.6%] in November. It increased markedly in 18-24-year-old population from 4.8% to 10.0%, and among second-generation immigrants from outside Europe from 5.9% to 14.4%. This group remained strongly associated with seropositivity in November, after controlling for any contextual or individual variables, with an adjusted OR of 2.1 [1.7–2.7], compared to the majority population. In both periods, seroprevalence remained higher in healthcare professions than in other occupations. Conclusion The risk of Covid-19 infection increased among young people and second-generation migrants between the first and second epidemic waves, in a context of less strict social restrictions, which seems to have reinforced territorialized socialization among peers.

Comparison of a Blood Self-Collection System with Routine Phlebotomy for SARS-CoV-2 Antibody Testing

“…Currently, there are limited data regarding the reliability of remote sample collection for SARS-CoV-2 antibody testing. Many seroprevalence studies for COVID-19 have used dried blood spot cards collected remotely [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ], but they can have a non-uniform blood distribution and uncertain collection volume [ 21 , 27 ]. One way to mitigate this issue of non-uniform blood distribution is the use of a volumetric sampling device, such as the Tasso-SST (Tasso, Inc, Seattle, Washington) device for capillary blood self-collection.…”

Risk factors for household transmission of SARS-Cov-2: a modelling study in the French national population-based EpiCov cohort

“…Family income and population density in the municipality of residence were associated with the probability of extra-but not intra-household infection, which allows a better understanding of the association of these factors with the seroprevalence previously described in the EpiCov cohort 11,12 . Surprisingly, we did not find an association between within-household person-to-person transmission and overcrowded housing or accommodation type, by opposition to some previous studies which reported associations between housing surface areas and secondary infection rates in households 27,28 .…”

“…This period covers the first two waves of the COVID-19 pandemic, mostly caused by the wildtype virus before the alpha variant gradually became dominant after its introduction at the end of 2020 18 and before the start of the vaccination campaign on December 27, 2020 19 . The epidemiological evolution during the year 2020 in France has been described elsewhere 12 and is briefly detailed in Supplementary Note 1.…”

Seroprevalencia de SARS-CoV-2 y factores asociados en migrantes con vocación de permanencia, Bucaramanga, Colombia

“…Por el contrario, la seroprevalencia en los migrantes con vocación de permanencia estudiados fue mayor a la reportada en tres estudios 19,20,21 . El primero realizado en la provincia de Hai Duong, Vietnam, entre enero y febrero de 2021, que incluyó un subgrupo de trabajadores migrantes, sintomáticos y asintomáticos, que se encontraban en dos instalaciones de cuarentena por tener contacto con convivientes con COVID-19, y que reportó una seroprevalencia de 0,47% (1/212) 19 .…”

“…El segundo estudio realizado en Francia, que incluyó población migrante de primera generación nacidos en Europa y fuera de Europa, encontró una seroprevalencia en mayo de 2020 de 3,8% y 9,2%, respectivamente en estas subpoblaciones. Además, para noviembre de 2020, la seroprevalencia aumentó a 5,2% en los migrantes nacidos en Europa y a 13,3% en los nacidos fuera de Europa 20 . Y el tercer estudio, realizado en Omán entre julio y noviembre de 2020 en población asintomática mayor de 4 años, que reportó una seroprevalencia en migrantes de 9,1% en la evaluación basal, la cual aumentó a 16,8% entre 8 y 16 semanas más tarde 21 .…”