an autodidact meets a dilettante…

Okay, before I look at the claimed dangers of vaccines in general, I’ll spend some time on diabetes, which, as mentioned, I know precious little about.

Diabetes mellitus, to use its full name, is a metabolic disease which causes blood sugar levels to be abnormally high. Some of the immediate symptoms of prolonged high blood sugar include frequent urination and feelings of hunger and thirst, but the disease can lead to many serious complications including kidney failure, heart disease and strokes. Diabetes is generally divided into type 1, in which the pancreas fails to produce enough insulin, and type 2, in which the body’s cells fail to process the insulin produced. Type 2, which accounts for some 90% of cases, can lead to type 1. There’s a third recognised type called gestational diabetes, a sudden-onset form occurring in pregnant women, which usually disappears after giving birth. As I’m not sure whether the claim about the MMR vaccine was related to type 1 or type 2, I’ll examine both.

type 1 diabetes and vaccination

A factsheet from Australia’s National Centre for Immunisation Research and Surveilance (NCIRS), a joint service of Westmead Hospital and Sydney University, and part of the World Health Organisation’s Vaccine Safety Net system of public information websites, summarises type 1 diabetes thus:

This is thought to be an autoimmune disease, where the immune system malfunctions to cause destruction of the insulin-producing cells in the pancreas. This is the usual type of diabetes in children, and requires treatment with insulin injections. Without insulin, people with Type 1 diabetes will die. Diabetes is thought to be due to an interaction between inherited and environmental factors, not all of which have been identified.

It goes on to describe an ‘unexplained’ increase in cases in Australia and many other (but not all) countries. There are regional variations in rates of increase, with higher rates in Northern European countries, lower in Asia and Africa, probably due to genetic factors. A number of  environmental factors that may also contribute to the incidence of the disease have been studied, including breast feeding, infections, immunisation, nitrates and vitamin D. Breast feeding slightly reduces the risk of contracting diabetes, and drinking cow’s milk may increase the risk. As to infections, few have been proven to cause diabetes – though one of them, interestingly, is mumps. Diabetes incidence is affected by seasonal variation, and it’s likely that seasonal viral infections may trigger the onset of diabetes in some people. It’s also possible that some strong medications may compromise the immune system and so cause or promote the onset of the disease. High levels of nitrates in drinking water have been shown to increase the incidence.

The factsheet is entitled ‘Diabetes and vaccines’, so it deals head-on with the vaccination issue, and its conclusion is uncompromising: ‘No, there is no evidence that vaccines cause diabetes’. It cites 15 separate studies in its reading list, three of which are authored or co-authored by a Dr John Classen. These three are the only studies to suggest a link. Here’s the NCIRS response:

There have been a number of studies which have searched for links between diabetes and immunisations. The only studies suggesting a possible increase in risk have come from Dr John B Classen. He found that if the first vaccination in children is performed after 2 months of age, there is an increased risk of diabetes. His laboratory study in animals also found that certain vaccines, if given at birth, actually decrease the risk of diabetes. This study was based on experiments using anthrax vaccine, which is very rarely used in children or adults. Dr Classen also compared diabetes rates with vaccination schedules in different countries, and interpreted his results as meaning that vaccination causes an increased risk of diabetes. This has been criticised because the comparison between countries included vaccines which are no longer used or used rarely, such as smallpox and the tuberculosis vaccine (BCG).

The study also failed to consider many reasons other than vaccination which could influence rates of diabetes in different countries. Later, in 2002, Dr Classen suggested that vaccination of Finnish children with Hib vaccine caused clusters of diabetes 3 years later, and that his experiments in mice confirmed this association.

Other researchers who have studied the issue have not verified Dr Classen’s findings. Two large population-based American studies failed to support an association between any of the childhood vaccines and an increased risk of diabetes in the 10 years after vaccination. The highly respected international Cochrane Collaboration reviewed all the available studies and did not find an increased risk of diabetes associated with vaccination.

Dr Classen, it turns out, is an established anti-vaxxer who has more recently tried to prove a link between vaccines and autism.

I should point out also that the above factsheet, which is a few years old, doesn’t include a more recent study, on a very large scale, which showed a significant decrease in the incidence of type 1 diabetes with various vaccinations, including MMR.

Classen, though, wasn’t looking at the MMR vaccine, his claims were about the Hib vaccine, which prevents invasive disease caused by the Haemophilus influenzae type b bacterium. It also significantly reduces the incidence of early childhood meningitis. The NCIRS factsheet doesn’t even mention MMR, stating that the vaccines being debated are Hib, BCG (for tuberculosis) and hepatitis B.

The Philadelphia Children’s Hospital’s Vaccine Education Centre (whose director, Dr Paul Offit, is one of the world’s leading immunologists and experts on vaccines), cites a long list of studies – have a look yourself – which together find no evidence of a causal connection between diabetes (mostly type 1) and various vaccines. I’ve yet to find any published studies, even poorly conducted ones, that claim a specific negative connection between the MMR vaccine and diabetes. If anybody out there can point me to such a study, I’d be grateful.

So, while I wait for someone to get back to me on this (ho, ho), I’ll explore what immunologists and epidemiologists are saying about the rise of type 1 diabetes in recent decades in my next piece.