While some people try to scare the world about the possible side-effects of vaccines, scientists are investigating them. Indeed, researchers have found vaccines against rotaviruses really do have an unintended effect – but it's a good one. Vaccinated children are a third less likely to develop type I diabetes.
Rotaviruses are the most common cause of diarrhea in young children – unpleasant for everyone, and responsible for hundreds of thousands of deaths in places lacking first-rate medical systems. In response, two vaccines are now in widespread use, one targetting the most common strain, while a more expensive version prevents five strains.
A recent study found an intriguing decrease in type 1 diabetes in Australia after the rotavirus vaccine was introduced. Dr Mary Rogers of the University of Michigan decided to see if this was more than a coincidence. Lest her findings were affected by small sample sizes, she used anonymized medical records of 1.47 million American children born since 2001. Of these, more than half a million had received a complete course of one or the other rotavirus vaccines.
In Scientific Reports, Rogers announces that children who received the entire vaccination schedule were 41 percent less likely to develop type 1 diabetes during the period of the study, with a greater reduction for those who received the pentavalent version. Those who were partially vaccinated had a rate effectively identical to those who were not vaccinated at all, but the smaller sample size makes conclusions here tentative.
During the time period of the study, most children immunized for rotavirus also received other vaccinations, usually around the same time. Rogers used comparisons with slightly older children, who received the rest of the schedule before the rotavirus vaccines became available, to confirm it is indeed the new addition that made the difference.
The effect was substantially larger among children born between 2012 and 2016 than those born before 2011. It's unclear if this is because the vaccine was improved in some way, or if in some cases it delayed, rather than fully prevented diabetes onset.
Rogers also examined the vaccine's effectiveness for its original purpose. The rate of hospitalization for rotavirus infections was an astonishing 94 percent lower for vaccinated than unvaccinated children.
As to any other side-effects; vaccinated children were 31 percent less likely to require hospitalization for any reason during the 60 days after they took the oral vaccine.
As unrelated as diabetes and rotavirus may seem, the virus can infect the pancreas, and there is evidence it leaves a legacy of damaged β-cells behind. However, the researchers caution they cannot show a simple cause-and-effect between the rotavirus vaccines and type I diabetes risk.
"This is an uncommon condition, so it takes large amounts of data to see any trends across a population," says Rogers in a statement. "It will take more time and analyses to confirm these findings. But we do see a decline in Type 1 diabetes in young children after the rotavirus vaccine was introduced."
The researchers suggest simply enforcing already existing shot recommendations could considerably reduce the burden of the chronic disease.