Mae NICE yn defnyddio’r diffiniadau clinigol canlynol ar gyfer y salwch cychwynnol a COVID hir ar wahanol adegau:COVID-19 acíwt: arwyddion o COVID-19 a symptomau am hyd at bedair wythnos.COVID-19 symptomatig parhaus: arwyddion o COVID-19 a symptomau am bedair i 12 wythnos.Syndrom ôl-COVID-19: arwyddion a symptomau, sy’n datblygu yn ystod neu ar ôl haint sy’n gyson â COVID-19, yn parhau am dros 12 wythnos ac nad ydynt yn cael eu hesbonio gan ddiagnosis arall.
NICE uses the following clinical definitions for the initial illness and long COVID at different times:Acute COVID-19: signs and symptoms of COVID-19 for up to four weeks.Ongoing symptomatic COVID-19: signs and symptoms of COVID-19 from four to 12 weeks.Post-COVID-19 syndrome: signs and symptoms that develop during or after an infection consistent with COVID-19, continue for more than 12 weeks and are not explained by an alternative diagnosis.