Since Doctor Edward Jenner first inoculated James Phipps back in the late 1700s, the primary purpose of vaccines has been to prevent the diseases for which they are intended. However, as the effects of the vaccines became known and more epidemiological studies were done on the populations receiving those vaccines, beneficial side-effects of vaccines became better understood. Recently, in the Journal of the American Medical Association (JAMA), a study of children receiving the rotavirus vaccine has shown that children who receive the vaccine have a lower risk of developing type I diabetes.
Type I diabetes, also known as “juvenile diabetes” because it is often first diagnosed in childhood, is the result of a non-functioning pancreas that is unable to create insulin. Insulin is a hormone needed for glucose (sugar) in the bloodstream to enter cells in the body and be used as energy. When insulin is not created, or is not functional because of some structural abnormality, the glucose remains in the bloodstream. As cells run out of glucose for fuel, the body begins to recruit fat and protein for fuel. This results in the creation of byproducts that make the blood more acidic, a situation that can lead to severe complications.
This new research is not a big surprise if you know about previous evidence of rotavirus infection damaging the pancreas and triggering type I diabetes in children. While there are genetic factors that trigger the disease, it seems that rotavirus infections cause damage to the insulin-producing cells. So it stands to reason that preventing rotavirus infections will prevent cases of type I diabetes that would have resulted from damage to those cells.
Interestingly, this is not the first time that a vaccine has shown unintended side effects against type I diabetes. A previous study looking at the use of the bacillus Calmette-Guérin (BCG) vaccine against tuberculosis showed that adults with type I diabetes had better blood glucose levels. In that study, researchers believe that the vaccine modulates an auto-immune response, preventing the body’s immune system from attacking the pancreatic cells that produce insulin. This is a follow-up to a similar trial published in 2012 by the same group of researchers.
As with all research, reproducibility of the findings is key to validating the results and making public health recommendations. However, public health authorities already have plenty of evidence to recommend the use of the rotavirus vaccine for preventing rotavirus infection and the severe diarrhea it causes, lowering the morbidity and mortality from the disease. That it may have these beneficial “side effects” is only a plus for what has been shown to be a safe and effective intervention.