* chronic (long-term) respiratory diseases, such as asthma, chronic obstructive pulmonary disease (COPD), emphysema or bronchitis
* chronic heart disease, such as heart failure
* chronic kidney disease
* chronic liver disease, such as hepatitis
* chronic neurological conditions, such as Parkinson’s disease, motor neurone disease, multiple sclerosis (MS), a learning disability or cerebral palsy diabetes.
* problems with your spleen – for example, sickle cell disease or if you have had your spleen removed.
* a weakened immune system as the result of conditions such as HIV and AIDS, or medicines such as steroid tablets or chemotherapy.
* being seriously overweight (a BMI of 40 or above).