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Childhood-diseases

28 May 2019

The authors of a study often used as the basis for kids skipping vaccines, say their research is now outdated

Eleven years after they authored a study which cast some doubts over the smallpox vaccine, two scientists say the methodology used has changed radically, and consider the research outdated.

Two scientists, Dr James Crow and Dr David Reif, published a paper in 2008 claiming that people with a variant for a certain gene (the MTHFR gene – responsible for providing instructions to the body to release an enzyme that plays a role in processing amino acids) should be exempted from receiving smallpox vaccinations as they “would be prone to adverse events”.

Now, 11 years later, the authors say the methodology for studying DNA has changed radically and the paper no longer holds any value, according to The Atlantic. Not only is the understanding of our DNA different after a decade, but the smallpox shot mentioned in the research is no longer administered as the disease is now eradicated.

The study, published originally in Journal of Infectious Diseases entailed linking the MTHFR gene to “systemic adverse events” (unpleasant reactions) after the smallpox vaccine is given.

The scientists administered the smallpox vaccine to over 130 healthy adults who were never previously vaccinated. The adults who had the MTHFR where more likely to develop adverse reactions, which included a mild fever, a rash and swollen lymph nodes.

Medical exemptions 

While these adverse conditions were not life-threatening in the slightest, those against vaccinations used this study to exempt their children from receiving vital vaccinations against other childhood diseases, including measles.

People would go so far as to order home DNA test kits to test for the MTHFR gene and get medical exemption from vaccinations.

The popularity of online DNA testing kits such as 23andMe has increased in the past few years.

The company published a blog post on their own website to try and stop people from using the MTHFR gene as an excuse from not vaccinating:

"Despite lots of research – and lots of buzz – the existing scientific data doesn’t support the vast majority of claims that common MTHFR variants impact human health,” 23andMe stated on their website in 2017. 

According to Dr David Reif, this 2008 research resurfaced in 2016, cited in a court case where a vaccine-skeptical tried to argue that it explained her patient’s delay in developments, according to The Atlantic.

This was not the only time this research paper was used in favour of those who are sceptical about vaccinations.

Lead study author Dr James Crowe said this study “is not even a valid study by today’s methodology” and that it’s “illogical and inappropriate” to use this research as a basis for vaccination exemption in today’s context.

Why people don't vaccinate (and why they should)

According to the World Health Organization (WHO), vaccine hesitancy, a reluctance or refusal to receive vaccinations despite availability, is a major threat to reverse the progress that was made in tackling vaccine-preventable diseases. 

Despite being one of the most cost-effective ways to avoid disease, the WHO has seen a 30% global increase in measles.

The reasons people choose not to vaccinate are complex and varied and is often based on research that is not solid enough.

Image credit: iStock