CEC-UW defines a “COVID-19 case” as any patient seen in any of the 21 participating health systems from February 1, 2020 to January 31, 2022, who met at least one of the following criteria:
- ICD-10 diagnostic code for COVID-19 (U07.1 or J12.82) and/or
- COVID-19 polymerase chain reaction (PCR) test positive result and/or
- COVID-19 antigen positive lab test
The cohort includes all healthcare system patients who met the COVID-19 case definition, and were seen in a variety of treatment settings – including hospitals, outpatient clinics, emergency departments, urgent care clinics, telehealth, and COVID-19 testing sites.
For specific analyses, only certain patients were included in those analysis samples. For example, if hospitalized patients were examined, only patients who received inpatient care for 24 hours or more were included in that specific cohort.