There are two main diseases we vaccinate against. It is not a big deal but prevention is better than cure.
You have probably seen one of those poorly rabbits with swollen eyes sitting near the road. It is a fatal disease and your rabbit can catch it from contact with hay and grass. The next wild rabbit is not far away and with them they can carry the risk of diseases.
Viral haemorrhagic diarrhoea
VHD is a highly infectious and often fatal disease. Symptomatic cases of VHD will display fever, squeals, and often coma leading to death within 12 to 36 hours. In less severe cases, rabbits may display uneasiness, excitement, anorexia, swollen eyelids, paralysis, ocular haemorrhages, and paddling.