Table 2 EHR data collected by the COVID-19 repository

• Verenso and one of the EHR software vendors developed a standardized COVID-19 form based on a template of openEHR [22].

• The form included patient information on:

◦ SARS‐CoV‐2infections (whether COVID-19 diagnostics have been started and whether COVID-19 is suspected, confirmed, or excluded);

◦ Follow-up information (whether a patient has recovered, shows clinical improvement or deterioration, has been admitted to a hospital, and has died in a nursing home or hospital).

• The COVID-19 repository collected data recorded in the COVID-19 form and additional general background information on the nursing home resident (age and sex) and on the nursing home location (total number of male/female residents, type of nursing home care ward).

• A pseudonymization tool developed by the trusted third party ZorgTTP [23] pseudonymized the data before the data were sent to the COVID-19 repository for storage.