Prior to December 2020 antibody tests were conducted by local health boards in Wales for surveillance of key groups working in health, social care and education.
Cyn mis Rhagfyr 2020, cynhaliwyd profion gwrthgyrff gan fyrddau iechyd lleol yng Nghymru ar gyfer gwyliadwriaeth ar grwpiau allweddol sy'n gweithio ym maes iechyd, gofal cymdeithasol ac addysg.