All individuals aged 16 years to 64 years with underlying health conditions (1), which put them at higher risk of serious disease and mortality.
Pawb sydd rhwng 16 a 64 mlwydd oed sydd â chyflwr iechyd sy’n bodoli eisoes(1), sy'n golygu eu bod mewn mwy o berygl o salwch difrifol a marwolaeth.