Mae ein dealltwriaeth o’r hyn sy’n gwneud rhywun yn agored iawn i effeithiau haint coronafeirws wedi datblygu, wrth i driniaethau newydd gael eu datblygu ac wrth i’r rhaglen frechu fynd rhagddi’n llwyddiannus.
Our understanding of what makes someone extremely vulnerable to the effects of coronavirus infection has developed, as new treatments have developed and alongside the success of the vaccination programme.