Table 1. COVID-19 test groups.

Test Group	Serology test results	RNA test results	Survey results on past COVID-19	Interpretation	No. of study participants
1	≥1 positive	≥1 positive	Any response	Infected with SARS-CoV-2 with evidence of an expected immune response	1537
2	≥1 positive	None or all negative	Any response	Not tested by RNA for SARS-CoV-2 (due to less severe infection or false-positive serology)	1338
3	All negative	≥1 positive	Any response	Presumptive impaired or waning immune response	379
4a	All negative	All negative	Reported no prior infectiona	Control	302
4b	All negative	All negative	Reported prior infectiona	Self-report (without record of positive RNA test in EHR data)	390

Abbreviation: EHR = electronic health record data.

^aBased on the question: “Did you have, or think you had, COVID virus infection?”.