Forgive me if this has been posted already, there are so many threads on Coronavirus, I'm finding it hard to keep up. It is pretty comprehensive.
Public Health England have this on their website.
We are advising those who are at increased risk of severe illness from coronavirus (COVID-19) to be particularly stringent in following social distancing measures.
This group includes those who are:
aged 70 or older (regardless of medical conditions)
under 70 with an underlying health condition listed below (ie anyone instructed to get a flu jab as an adult each year on medical grounds):
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 body mass index (BMI) of 40 or above)
those who are pregnant
Note: there are some clinical conditions which put people at even higher risk of severe illness from COVID-19. If you are in this category, next week the NHS in England will directly contact you with advice the more stringent measures you should take in order to keep yourself and others safe. For now, you should rigorously follow the social distancing advice in full, outlined below.
People falling into this group are those who may be at particular risk due to complex health problems such as:
people who have received an organ transplant and remain on ongoing immunosuppression medication
people with cancer who are undergoing active chemotherapy or radiotherapy
people with cancers of the blood or bone marrow such as leukaemia who are at any stage of treatment
people with severe chest conditions such as cystic fibrosis or severe asthma (requiring hospital admissions or courses of steroid tablets)
people with severe diseases of body systems, such as severe kidney disease (dialysis)
. Sounds like they, traditionally contain ? s too! How come I, of all people 
, lived all this time without knowing that! They also sound scrummy so I will have to make it my mission to find a good recipe.