MS is an auto-immune disease, where elements of the body’s immune system malfunction and attack healthy body tissue, in the case of MS a type of tissue that supports nerve fibres and their function. Other aspects of the immune system such as the ability to fight infections are not normally affected, hence the disease per se does not increase vulnerability to infection, and thus does not qualify. However if an individual’s treatment involves immunosuppressant therapy , ie the treatment makes them more vulnerable, they might qualify. That sadly does not take into account the severe physical debility that can result from MS, it is a nasty and unpredictable disease, and Chris, if I have not misunderstood the implication that you have the condition, you have my best wishes and hopes for prolonged remission.
Jerry