MTHFR and Vaccines

The majority of studies suggest that vaccines do not cause vaccine injury or other serious health conditions in people with MTHFR mutations.¹ This includes vaccines for Covid-19, HPV (human papillomavirus), the flu, MMR (measles, mumps, and rubella), Hepatitis B, shingles and chicken pox.²

However, some sources suggest otherwise. A few studies have shown that factors such as genetics (including MTHFR), infections, immune status and overall toxic load may affect how someone responds to a vaccine. 

It has already been found that increased homocysteine (common among those with MTHFR) may result in a more severe COVID-19 infection and longer recovery.³

Although research is currently limited, a 2023 systematic review on MTHFR and COVID‑19 found that those with MTHFR mutations may have an increased risk of thromboembolic events such as pulmonary embolism, thrombosis and ischemic stroke after vaccination. Four out of eight studies in the review indicated a connection between MTHFR mutations and severity of a COVID-19 infection.⁴ The researchers noted that larger studies are needed to confirm this strong association between MTHFR, thromboembolic incidents and the vaccine. This continues to be an active area of research.

Previously, a 2008 study suggested a possible link between the MTHFR C677T mutation and mild adverse events after the smallpox vaccine. However, the smallpox vaccine is no longer given to the public.⁵

MTHFR gene variants - especially C677T and A1298C - result in impaired methylation, which directly reduces the production of glutathione, the body's master antioxidant. Poor methylation also leads to elevated homocysteine, which is linked to higher oxidative stress and DNA damage burden in cells.⁶

A 2022 study suggested that people affected by oxidative and genotoxic stress may have a weaker antibody response to a vaccine. 

Higher pre‑vaccine DNA damage in immune cells was correlated with a poorer antibody response to the COVID-19 vaccine. This indicated that oxidative and genomic stress may weaken vaccine‑induced humoral immunity.⁷
While this study focused on older people, people with MTHFR mutations who have high homocysteine and low glutathione are also affected by greater levels of oxidative stress. ⁸

This highlights the importance of managing homocysteine levels and supporting glutathione production. 

The HPV vaccine is designed to prevent infections and diseases caused by specific types of the human papillomavirus, including those that can lead to cancers. There is no current evidence that suggests a link between the MTHFR gene mutations and adverse effects of the HPV vaccine.
However, it is worth noting that the Vaccine Adverse Event Reporting System (VAERS) analysis of the HPV vaccine Gardasil 9 from 2015-2024 classified 7.5% of adverse events as ‘serious’. These included life‑threatening illness, hospitalization, permanent disabilities, postural orthostatic tachycardia syndrome (POTS), seizure, syncope, loss of consciousness, migraine, anxiety, muscular weakness, rash, erythema, abdominal pain, and gait disturbance.⁹

The authors of the analysis concluded that while most reports (92%) of adverse events were not serious, they emphasized the high occurrence of POTS and other neurologic, autonomic, and autoimmune conditions are not currently mentioned in Gardasil 9 prescribing information and should be investigated further.¹⁰

The MTHFR C677T is frequently associated with a higher risk of autism (ASD), primarily due to reduced function of the MTHFR enzyme resulting in impaired folate metabolism.¹¹ Recently, a 2026 meta-analysis concluded that there is a significant association between ASD and the MTHFR C677T variant.¹²

Several epidemiologic studies have not found an association between vaccinations and autism, including a study that found that the MMR vaccine did not increase risk of autism even among children whose siblings had autism.¹³ However, other researchers have suggested that the MMR vaccine can lead to gastrointestinal disorders and subsequent developmental regression, which they have then linked to autism. Although this link has not been confirmed in scientific literature, many parents are still hesitant about vaccinations.

A 2021 review noted that diagnoses of autism often occur after the age at which children receive major childhood immunizations, which may explain why the two variables have been linked.¹⁴

Significant anecdotal evidence suggests that certain people are at higher risk of vaccine injury, including people who are severely immunocompromised or have complex chronic illnesses such as Lyme disease, multiple infections, high toxic burden, poor nutritional status, and/or impaired methylation. It has been suggested that these people may have lower baseline resilience to vaccinations.

Chronic health conditions such as Lyme disease, ASD, MTHFR and other SNPs are often associated with poor methylation. Methylation is essential for healthy cellular function and systemic detoxification as it is key to the production of glutathione, the body’s major antioxidant. Glutathione plays a major role in the body’s detoxification pathways and the immune response. Studies have already suggested that glutathione depletion may have a central role in COVID-19 mortality and pathophysiology.¹⁵

Some sources have also argued that low levels of glutathione could affect the body’s response to the COVID vaccination. Further research is pending.

General evidence to date suggests that those with MTHFR can safely receive a vaccine, but it’s important to consider your own health circumstances which could complicate that safety. However, some research has noted that many single-nucleotide polymorphisms (SNPs) in genes involved in coding for vitamin receptors are associated with variations in vaccine responses.¹⁶ MTHFR is also an SNP, but specific research regarding complications between MTHFR and vaccines is currently limited.
It’s also important to note that many factors can affect your immune response to vaccination, including intrinsic factors (age, sex, genetics and comorbidities), extrinsic (preexisting immunity, microbiota, infections, use of antibiotics), environmental (geographic location, season, family size and toxins), lifestyle (smoking, alcohol consumption, exercise and sleep), and nutritional (body mass index, micronutrient status).¹⁷

If you have an MTHFR mutation and you are unsure about any vaccine, it’s best to discuss your needs and health status with a healthcare professional.