Question explored with the scientific record
Can the covid vaccine cause a vitamin b12 deficiency
The short version: one case report found a B12 deficiency in a vaccinated patient, but that is not evidence the vaccine caused it.
The only evidence here is a single case report of a patient who developed acute transverse myelitis after a Moderna mRNA vaccine and was found to have a vitamin B12 level of 131 pg/mL, well below the deficient threshold of 211 [1]. The report notes the B12 deficiency as a pre-existing condition, not a new finding caused by the vaccine. The patient had an elevated MCV of 113.7 fL, which is a classic red-flag for B12 deficiency that predates the vaccination [1]. No other study in the retrieved evidence measures B12 levels before or after vaccination. No trial, no cohort, no systematic review addresses the question.
The evidence does not show that COVID-19 vaccination causes B12 deficiency. It shows that a person with undiagnosed B12 deficiency had a rare autoimmune complication after vaccination. That is a different claim entirely. The mechanism is plausible in theory—the spike protein and inflammation can disrupt blood colloid stability and nutrient transport—but no study in this evidence set tests it. The gap itself is the finding.
My call: the evidence does not support a causal link between COVID-19 vaccination and B12 deficiency. Confidence: low, because the question was never studied.
Sources examined 12
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Acute Transverse Myelitis Following COVID-19 Vaccination
This case report describes a rare instance of longitudinally extensive transverse myelitis (LETM) occurring shortly after vaccination with the Moderna COVID-19 mRNA vaccine, highlighting potential autoimmune responses triggered by the vaccine in a patient with vitamin B12 defici…
DOI: 10.3390/vaccines9091008 -
Erythema Migrans-like COVID Vaccine Arm: A Literature Review
This literature review investigates the adverse skin reaction known as COVID Vaccine Arm (CVA), characterized by erythema and edema at the vaccination site, and its implications following mRNA COVID-19 vaccinations.
DOI: 10.3390/jcm11030797 -
Asian-Origin Approved COVID-19 Vaccines and Current Status of COVID-19 Vaccination Program in Asia: A Critical Analysis
A critical analysis mapping Asian-origin COVID-19 vaccines and the status of vaccination programs across Asia as of March–May 2021, detailing vaccine platforms, clinical trials, regulatory approvals, demographic coverage, and cost considerations.
DOI: 10.3390/vaccines9060600 -
COVID-19 vaccination-related small vessel vasculitis with multiorgan involvement
This study reports a case of a 77-year-old woman who developed small-vessel vasculitis with multiorgan involvement following the administration of the Pfizer-BioNTech COVID-19 vaccine, highlighting potential autoimmune side effects of COVID-19 vaccinations.
DOI: 10.1007/s00393-022-01159-8 -
The Impact of COVID Vaccination on Symptoms of Long COVID: An International Survey of People with Lived Experience of Long COVID
An international, cross-sectional online survey of 812 adults with long COVID found that a first COVID vaccination was associated with overall symptom improvement in 57.9% of participants and deterioration in 17.9%, with greater average improvement for Moderna and Pfizer vaccine…
DOI: 10.3390/vaccines10050652 -
Who Is Really at Risk for Anaphylaxis Due to COVID-19 Vaccine?
An expert commentary reviews early anaphylaxis reports after Pfizer-BioNTech COVID-19 vaccination and proposes a pragmatic risk-stratification protocol, arguing the MHRA's broad contraindication is overly restrictive.
DOI: 10.3390/vaccines9010038 -
COVID- 19 vaccination reduces new-onset fibromyalgia risk in survivors
This study investigates the protective effect of COVID-19 vaccination on the risk of new-onset fibromyalgia in COVID-19 survivors, finding a significant reduction in risk among vaccinated individuals compared to unvaccinated ones.
DOI: 10.1186/s12916-025-04069-z -
Minimal Change Disease After First Dose of Pfizer-BioNTech COVID-19 Vaccine: A Case Report and Review of Minimal Change Disease Related to COVID-19 Vaccine
This case report documents a 60-year-old man who developed de novo minimal change disease with nephrotic syndrome and acute kidney injury approximately 10 days after a first dose of the Pfizer-BioNTech COVID-19 vaccine, was treated with steroids leading to remission, and is disc…
DOI: 10.1177/20543581211058271 -
The development of China’s vaccine industry in the past decade: the perspective from drug regulatory science
This paper analyzes China’s vaccine industry from a regulatory science perspective over 2011–2020, showing stable overall vaccine production with growth in new and multi‑disease vaccines, ongoing improvements in regulatory standards, and rapid development/approval of vaccines du…
DOI: 10.1080/21645515.2021.2002640 -
Vaccination Coverage in Adult Patients with Inflammatory Bowel Disease: Impact of a Tailored Vaccination Pathway Including COVID-19 and Herpes Zoster in a University Hospital Vaccination Center
A single-center, observational study at the University Hospital Vaccination Center in Messina, Italy, showing that a tailored, multidisciplinary vaccination pathway for adults with inflammatory bowel disease substantially improved vaccination coverage for influenza, pneumococcal…
DOI: 10.3390/vaccines13090961 -
Overview of Knowledge Levels of People Who Are Willing to Vaccinate Against COVID-19 in the COVID-19 Vaccination Program at RSUMM
This study investigates the knowledge levels of individuals willing to vaccinate against COVID-19 at RSUMM, revealing that 87% of respondents demonstrated good knowledge, primarily sourced from social media.
DOI: 10.18502/kme.v3i2.13062 -
Risk of flare or relapse in patients with immune-mediated diseases following SARS-CoV-2 vaccination: a systematic review and meta-analysis
This systematic review and meta-analysis assess the risk of flare or relapse in patients with autoimmune and immune-mediated diseases following SARS-CoV-2 vaccination, finding a minimal overall prevalence of 6.28%, particularly lower with vector-based vaccines.
DOI: 10.1186/s40001-024-01639-4