This work uses non-identifiable data provided through the use of the DoH NI app, ‘COVID-19 NI’. The app was produced on behalf of the DoH by Digital Health and Care Northern Ireland (DHCNI) and the Public Health Agency for Northern Ireland, working with commercial partners Civica and BigMotive. We wish to acknowledge the access granted to the non-identifiable data, which led to this output. This work is partially funded by national funds through the FCT — Foundation for Science and Technology, I.P., Portugal, within the scope of the project CISUC — UID/CEC/00326/2020 and by European Social Fund , through the Regional Operational Program Centro 2020.