The rotavirus vaccine, which helps prevent severe bouts of dehydrating diarrhoea in infants, may also protect against type 1 diabetes.
Melbourne researchers have found the incidence of type 1 diabetes dropped 14% after the introduction of two oral rotavirus vaccines in 2007.
The majority of infants now receive the rotavirus vaccine in Australia. But children aged 12 and over were not vaccinated against rotavirus as infants, and therefore missed out on any potential protection against type 1 diabetes.
Dr Kirsten Perrett, lead author of the study and a clinician-scientist at the Murdoch Children’s Research Institute, said the timing of the dip in type 1 diabetes rates supported the hypothesis that the rotavirus vaccine might be having a protective effect.
While this was only a preliminary study, but it was difficult to think of anything else that happened in 2007 that could explain the result, she said.
The researchers drew from publicly available data on children with type 1 diabetes, which was recorded by the National Diabetes Services Scheme between 2000 and 2015.
However, any shield against type 1 diabetes conferred by the rotavirus vaccine might be transient, as it was unknown whether it would persist as the children got older, Dr Perrett said.
The paper builds on 20-year old research by Professor Len Harrison, a scientist at the Walter and Eliza Hall Institute in Victoria and a senior author on the paper. Professor Harrison used mouse models and laboratory studies to show the rotavirus infection of pancreatic cells could trigger an immune attack against the insulin-producing cells.
This suggested that rotavirus infection might be associated with type 1 diabetes in a minority of infants who were already genetically at risk.
However, it was unclear whether the negative association between rotavirus vaccination and type 1 diabetes would hold true for children in other countries, Dr Perrett said. Around 90 countries across the globe now routinely administer the rotavirus vaccine to infants.
But the rates of type 1 diabetes differs from country to country. Finland, for example, has the highest rate of type 1 diabetes in the world. Between 2006-2011, the mean incidence of type 1 diabetes in Finnish children under 15 years was 63 per 100,000 per year, while the incidence in Australian children in the same age group in 2000-2013 was 13 per 100,000 per year.
It was possible that changes in type 1 diabetes rates and response to rotavirus vaccination could vary by geographical location due to a range of environmental, lifestyle and genetic factors at the population level, Dr Perrett said.