Socio-economic inequalities and the COVID-19 epidemic in France: territorial analyses by epidemic wave and by metropolitan area

Background Previous studies highlighted the relationships between socioeconomic inequalities and the population’s risk to become disease or die during COVID-19 epidemic. In France, socioeconomic inequalities vary across metropolitan areas, but little is known if that could explain the spatial disparities observed in terms of incidence and testing rates. We assessed the impact of socioeconomic inequalities on testing and incidence rates of COVID-19 for each metropolitan area and wave.

For each of the 22 metropolitan areas, we relied on socioeconomic variables from census data to define socioeconomic profiles using classification on the principal components. We analysed associations between socioeconomic profiles, testing and incidence rates by epidemic wave from July-2020 to March-2023, using spatialised generalised additive mixed models. We performed meta-regressions to study the distribution of testing and incidence rate ratios (socially deprived vs privileged) across metropolitan areas, according to vaccination rates.

Socially deprived metropolitan areas had lower testing rates than privileged, but during wave 4 (July-October-2021, extended health pass), testing rates increased in more deprived areas. Incidence rates were higher in deprived areas (waves 2-4, July-2020 to October-2021) but reversed between waves 6 to 9 (March-2022 to March-2023). Meta-regression analysis indicated that high vaccination coverage narrowed testing and incidence gaps between deprived and privileged.

The impact of social inequalities on the population’s testing and incidence COVID-19 epidemic was driven by socioeconomic inequalities across metropolitan areas and varied across epidemic waves. Vaccination rates and the presence of health measures (lockdowns, health pass) seem to help reduce these disparities. Competing Interest Statement The authors have declared no competing interest. Funding Statement This study was funded by Sante publique France and Interdisciplinarity A*MIDEX, Initiative of Excellence Aix-Marseille - ANR-11-IDEX-0001-02. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the Ethics Committee of Aix-Marseille University (number 2022-10-20-006). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data availability The aggregated data are accessible to researchers upon reasonable request for data sharing to the corresponding author. Requests for data require approval by Santé Publique France. Requests to access these datasets should be directed to the corresponding author.