Using R values in February 2021 and improvements to case ascertainment and test and trace times, the effect may have been a reduction from approximately 1.3 to 0.8.
Gan ddefnyddio gwerthoedd R ym mis Chwefror 2021 a gwelliannau i ganfod achosion ac amseroedd profi ac olrhain, gallai'r effaith fod wedi bod yn ostyngiad o tua 1.3 i 0.8.