COVID-19 is a disease caused by a new coronavirus that affects the lungs and airways. It is related to viruses that cause the common cold. Unlike the common cold, this virus is new, so nobody has immunity to it.

The entire population is therefore at risk of catching it. It is estimated that as many as 80% of people who catch the virus may experience relatively mild or no symptoms but are able to pass on the infection to others. People who do develop symptoms are at risk of passing it on to others for up around 7 days before symptoms emerge. The commonest symptoms are high fever, cough, or shortness of breath.

People aged over 70, with long-term conditions or a weakened immune system are at risk of developing complications of the infection, including secondary lung infections or damaging excess activity of the immune system.

Some patients with particular neurological conditions, who receive certain treatments for neurological conditions, or who also have other non- neurological conditions are at increased risk of complications of COVID-19.