Yn ogystal â’r brechlyn, mae triniaethau gwrthfeirol newydd wedi helpu i leihau difrifoldeb y clefyd, yn arbennig i’r rheini sydd fwyaf tebygol o’i gael yn wael.
As well as the vaccine, new anti-viral treatments have helped to reduce the severity of disease, particularly for those who are most likely to be at risk of adverse outcomes.