Type 1 diabetes is a disease that occurs when the pancreas stops producing insulin. Type 1 diabetes occurs most commonly in children and is often the result of the immune system destroying beta cells in the pancreas. Beta cells are the cells in the pancreas that make insulin. Rotavirus is a genus of RNA viruses that can cause infections in people throughout most of the world. Infection by Rotavirus causes sickness and diarrhoea in babies and young children, and may damage the pancreas. Rotavirus infections are also associated with the development of type 1 diabetes in children. In May 2007, a vaccination against Rotavirus was introduced in Australia. All babies aged from 2 months to 4 months were offered the Rotavirus vaccine. Some scientists decided to investigate whether vaccination against Rotavirus had reduced the number of children with type 1 diabetes in Australia.