You may have read or heard that anyone who carries MTHFR variants should not be vaccinated. Usually, the reason given is that those with decreased MTHFR enzyme activity cannot detoxify or ‘handle’ vaccinations, often with references to mercury in the vaccines.
This article reviews the published scientific studies on the topic of MTHFR and vaccinations.
The MTHFR gene codes for the enzyme that plays a critical role in using folate in the methylation cycle. There are two genetic variants of MTHFR that many researchers have focused on. These two variants are known as C677T and A1298C. (Read more and check your 23andMe data here: How to check your genetic data for MTHFR.)
I purposefully refer to the genetic change in MTHFR as a variant instead of a mutation. At least one copy of the C677T variant is found in over half the people in most population groups. This is not a rare mutation, but rather a common variation that causes a change in how the gene functions.
Researching the studies on MTHFR variants and vaccination injuries or adverse events lead me to exactly one study. Seriously. One study — on a vaccine that is no longer given.
It is an open-access article on genetic variants and adverse reactions to the smallpox vaccine.
Overview of the study: In a study conducted by Vanderbilt University, 131 people (average age of 23) received a vaccine for smallpox. The results showed that those individuals with an MTHFR C677T variant were more likely to have an adverse reaction to the vaccination. The study also linked other genes to an increase in adverse events.
Adverse events were defined as a skin reaction at the site of injection, fever within 30 days of the vaccine, or enlarged or tender lymph nodes. 40 study participants reacted to the vaccine and 69 participants did not.[ref] Smallpox vaccines have not been used on the general public in the US in over 46 years, and none of the study participants had previously received a smallpox vaccine. The vaccine contains a live virus that is similar to smallpox. It is given only to those who are at risk of smallpox exposure. [ref]
update! Read why the author of that study does NOT think it shows a reason not to vaccinate: article in The Atlantic.
Some claim that excipients added to vaccines are the reason that MTHFR C677T variant carriers should not be vaccinated.
There was a small study done showing that people with the MTHFR C677T variant might be more sensitive to mercury. The study looked at the genes of 25 participants that had been diagnosed as sensitive to mercury compared with a control group of 25. The MTHFR 1298C/C genotype was more common in the mercury-sensitive group. (Note that the study had a very small group size.)
But… Mercury has been removed from children’s vaccinations since 2001 in the U.S. Seasonal flu vaccines for those over 6 years old can still contain mercury, so check the ingredients on that particular vaccine if you are concerned about mercury.
I didn’t find any other links between MTHFR variants and other common excipients in vaccines.
A study on vaccines and MTHFR that (hopefully!) doesn’t apply to children found that a cocaine vaccine worked better for MTHFR 677T/T genotype (decreased cocaine use and depression scores).[ref]
The ‘conspiracy theorist’ in the back of my mind wondered if the link between MTHFR and vaccine injuries was just being covered up — or perhaps deliberately not studied.
But… that doesn’t seem to be the case.
There are quite a few studies that look at the interaction between genetics and vaccination reactions. The studies cover how different genetic variants increase or decrease the effectiveness of vaccines as well as how genes interact with adverse events.
One study found quite a few HLA gene variants as well as other immune system gene variants that do play a role in how vaccines work. The study examined the response to measles vaccinations and found that HLA type predicted whether the recipient would have a strong or weak immune response to the vaccine.[ref] Another study found that CD46 genetic variants also influenced the response to the measles vaccine.[ref]
These immune system genes make sense to influence vaccine response — a lot more sense than the MTHFR variant. So instead of a conspiracy, it may be more the case that studying the MTHFR variant in conjunction with vaccines just doesn’t make a lot of sense.