Mae mwy na miliwn o bobl eisoes wedi cael eu pigiad atgyfnerthu yng Nghymru, ond mae’r rhaglen yn cael ei chyflymu’n dilyn ymddangosiad yr amrywiolyn hwn sy’n lledaenu’n gyflym.
More than a million people have already received their booster vaccine in Wales but the programme is being speeded up following the emergence of the fast-moving variant.