In the UK annual flu vaccination has been offered to individuals in the highest risk groups since the 1960s and to all people over 65 for more than 20 years.
Yn y DU, mae brechiad ffliw blynyddol wedi'i gynnig i unigolion yn y grwpiau risg uchaf ers y 1960au ac i bawb dros 65 oed ers dros 20 mlynedd.