Risks of measles include
1 in 12 chance of ear infection and temporary deafness, this will lead to permanent deafness for some people.
1 in 16 chance of pneumonia or other respiratory complications.
1 in 12 chance of diarrhoea severe enough to require treatment for dehydration.
1 in 1000 change of encephalitis, this is a life threatening condition requiring ICU treatment and has a mortality rate of approximately 30%.
There is a risk also of developing a condition called SSPE which is a progressive destruction of the central nervous system and is fatal. It killed Roald Dahl's daughter in 1962.
Contracting measles wipes out T lymphocyte cells, destroying immunity to other diseases. It can take the body up to three years to recover from this, leaving that person susceptible to many other diseases and infections including ones they were previously immune to. The vaccine does not cause this same weakening of the immune system.