Like coronvirus, it is caused by a virus and it can lead to illnesses such as bronchitis and pneumonia, which may need treatment in hospital.
Fel Coronafeirws, mae'n cael ei achosi gan feirws a gall arwain at afiechydon fel broncitis a niwmonia, ac mae’n bosibl y gallai arwain at yr angen am driniaeth yn yr ysbyty.