Vaccines are an area of much concern for people with the MTHFR mutation for a number of reasons. One, is that with a compromise in MTHFR, it is much more difficult to detoxify heavy metals and many vaccines use heavy metals including aluminum and mercury. Also, vaccines have been controversially implicated in increasing risk of autism and spectrum disorders, and people with the MTHFR mutation have shown to be at greater risk for developing these issues. Still, there is only one research study showing a correlation between MTHR and adverse vaccine reactions, and it is a study on the smallpox vaccine, which is not routinely given in the US. Largely, this type of research has not been conducted and so we can only hope that the gaps in our knowledge will be corrected. Even in the Vaccine Adverse Event Reporting Database there are limited entries that include MTHFR because the database relies on self-reported symptoms and information and most people with the MTHFR polymorphism are unaware that they have it.