Identifying sources of heterogeneity in contact patterns is key to inform disease transmission models. Recent works have investigated how individual-based socio-economic factors, besides age, affect contact behaviour, but neglected the individuals’ area of living. Here, we aimed at estimating contact matrices stratified by both individual-based and area-based socio-economic factors. We used social contact data from Switzerland collected in 2021, combined with a neighbourhood-based index of socio-economic position (SEP). First, we found a positive association between education level and number of contacts in the elderly, and, notably, a negative association between SEP level and number of contacts in adults. Second, despite lacking socio-economic information on the contacts, we developed a method to reconstruct contact matrices fully stratified by age, education level, and SEP, with varying assortativity levels. Third, integrating the matrices into a transmission model revealed heterogeneous disease burden, with higher attack rates in adults with higher education level living in low SEP areas and seniors with higher education level living in high SEP areas. Adults and young individuals living in high SEP areas were the main contributors to transmission. We found that the less assortative contacts are, the higher the chances of a targeted strategy to be successful, and the lower the control effort required to prevent disease spread. Our results shed light on contact behaviour in previously neglected socio-economic groups, enable model integration of socio-economic indicators, and provide insights to improve disease control.

The authors have declared no competing interest.

This work has received funding from the ESCAPE project (101095619), funded by the European Union, and the Swiss State Secretariat for Education, Research and Innovation (SERI) (22.00482). The work was further supported by the Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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:

The CoMix study protocols and questionnaires were approved by the local ethics committee of the Canton of Bern (project number 2020-02926). All methods were performed in accordance with regulations and informed consent of participants was obtained.

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

Population and household statistics, and the dataset with the SEP index are available under request from external providers. All other population datasets used in this study are openly available. The social contact data, with a subset of variables for participants, are available on Zenodo; the full dataset can be obtained by the authors under request. The code used to run the analysis is available on Github at https://github.com/ISPMBern/comix_SEP.