Document text
Wafik El-Deiry , MD, PhD, FACP
Director, Legorreta Cancer Center
Associate Dean, Oncologic SciencesWarren Alpert Medical School, BrownUniversity
September 19, 2025
Workgroup Safety Uncertainties of mRNA
COVID Vaccines
Charlotte Kuperwasser, PhD
Director, Tufts Convergence Laboratory of
Biomedical, Physical, and Engineering SciencesProfessor Developmental, Molecular & Chemical Biology, Tufts University School of Medicine
TERMS OF REFERENCE # 6, 7 & 8
1.Immune Changes
2.Biodistribution
3.Frameshifting
4.ImpuritiesSummary of Workgroup Activities for
TORs
Immune Changes
COVID vaccination, especially multiple doses, can lead to the
following immune responses:
•IgG4 class switching 1
•Production of anti -idiotype antibodies 2,3
•Low long- term IgG Fc galactosylation and sialylation levels 4
•Persistent cytokine changes5,6
1)Irrgang et al. Sci Immunol (2023)
2) Murphy et al . N Engl J Med (2022).
3)Bellucci et al. Front Immunol. 2024
4)Buhre , et al. Front Immunol (2023)
5)Alghamdi et al. Immun Inflamm Dis ( 2025)
6)Cabău et al. Vaccines (2024)
7) Bhattacharjee et al. & Iwasaki A medRxiv (2025)
8) Noé, A. et al. Front Immunol (2023).
9)Yamamoto, M. et al. J Cut Immun and Allergy (2022)
10)Park, H et al. Science Trans Med (2025).
•Reduction in circulating memory and effector CD4 T
cells, and increases in TNFα+ CD8 T cells 7
•Risk of more persistent and/or recurring infections 8-10
Immune Summary
•The persistence, clinical significance, and potential long- term
consequences of these immune changes is uncertain.
•More research is needed to understand vaccine non- specific
effects on innate and adaptive immunity and its ability to
reprogram innate and adaptive immune cells. Covid vaccine safety issues
Pfizer -Comirnaty
High levels detected in:
-Injection site
-LiverFDA Summary Basis for
Regulatory Action (SBRA)
Used a luciferase reporter mRNA (instead of spike mRNA) in mice and rats, delivered in the same lipid
nanoparticles (LNPs). Also tested biodistribution/metabolism of Pfizer’s two novel lipids (ALC -0315 and ALC-
0159):
IM injection in mice:Biodistribution
Biodistribution
Moderna- SPIKEVAX
High levels in:
-Draining lymph nodes
-Spleen
-Eye
-Liver
•Low levels detected in many tissues including:
-Heart, lung, testis, brain
•In brain, ~2– 4% of plasma levels (so trace crossing of the blood– brain barrier).FDA Summary Basis for
Regulatory Action (SBRA)
States no biodistribution study was performed with mRNA -1273; instead, FDA reviewed a biodistribution
study of a different mRNA vaccine made with the same SM -102 LNP, considered those results supportive for
Spikevax.
Biodistribution
Vaccine
mRNA in humansSitePersistence After
Vaccination Reference(s)
Axillary lymph node Up to 30 days Krauson et al. NPJ Vaccines (2023)
Heart
(myocardium/cardiac ventricles)Up to 30 days1.Yonker et al., Circulation (2023)
2.Boros et al, Pharmacol Res Perspect
(2024)
3.Krauson et al. NPJ Vaccines (2023)
Blood ~15 days to 23 months1.Patterson et al, Hum Vaccin
Immunother (2025)
2.Ogata et al, Clin Infect Dis (2022)
3.Fertig et al, Biomedicines (2022)
4.Bhattacharjee et al. medRxiv (2025)
5.Brogna et al. Proteomics Clin Appl
(2023)
CNS
(skull/meninges/ Cerebral arteriesUp to ~17 months1.Ota et al. J Clin Neurosci (2025)
2.Luis et al Brain Behav Immun Health
(2021)
Breast milk 45 hours Hanna et al. JAMA Pediatr (2022)
Biodistribution Summary
•Neither Moderna or Pfizer biodistribution studies used
commercial product for testing.
•Neither Moderna or Pfizer biodistribution data showed confinement to site of injection. Distribution included draining
lymph nodes, liver, spleen, heart, brain, lungs, and blood. It was noted that it could cross the BBB.
•Covid vaccine mRNA has been detected in multiple tissues in humans including lymph nodes, heart, CNS, blood, and
others.
•Covid vaccine mRNA has been reported to persist for up to 706 days.Covid vaccine safety issues
Frameshifting
Off-target protein production
1) Mulroney, T. E.. Nature 625, 189- 194 (2024).
2) Boros, L. G. et al. . Pharmacol Res Perspect (2024). •Therapeutic/in vitro- transcribed (IVT) mRNAs often contain
modified nucleotides (ribonucleotides), such as N¹-
methylpseudouridine to help reduce innate immune activation
and increase stability.
•Nucleoside- modified mRNA is synthetic and not a natural
mRNA.
•This modification instructs cells to produce off -target proteins
due to ribosomal slipping 1,2.
Covid vaccine safety issues
•There is evidence that these unintended/off -target proteins
generate an immune (T cell) response in humans 1
•Immunogenic or toxic properties of the non- spike proteins is
unknown.
•The health consequences of prolonged and persistent non-
spike protein production have not been studied Frameshifting
1) Mulroney, T. E.. Nature 625, 189- 194 (2024).
Impurities
Sources during manufacturing
1. Incomplete Digestion (DNAse )
2. Separation Challenges
1.Speicher, D. J., et al .(2025).
2.McKernan, K. (2023).
3.Raoult, D. (2024).
4.Kaiser, S., et al (2025).
5.Kämmerer , et al (2024).
6.Buckhaults , P. (2023).
7.König, B. (2024).
8.Wang et al (2024). DNA impurities in vaccines have
been reported in the following:
SV40 promoter -
enhancer ‐oriUnexpected impurities
Pfizer
Moderna
Differences between Pfizer vs Moderna
Pfizer/Comirnaty Moderna/Spikevax
Vector used for generating the
DNA templateBacterial plasmid that contains
mammalian -cell expression
elements, including SV40
promoter/enhancer sequences.Bacterial plasmid
Foreign DNA material of
concernSV40 promoter/enhancer -oriFull nucleotide sequences have not
been published
DNA fragment sizes &
quantityMean ~214 bp, maximum ~3.5 kb
~ 371-1,548 ng per dose* Similar fragmented distribution,
but maximum size smaller, consistent with smaller plasmid
backbone.
~ 1,130 -6,280 ng per
dose*
Clinical trial vs marketed
productClinical trials used a clean PCR
product template. Commercial product uses plasmid. No clinical trial was conducted on
marketed product . Same product on market as clinical
trial
*FDA limit of
10 ng set for naked DNA, not DNA in presence of LNP that carries DNA into cells and their nuclei.
Covid vaccine safety issues
•Pfizer vaccine: Exceeds limits1by ~36- 153-fold and SV40
promoter/enhancer sequences detected2.
•Moderna: Exceeds limits1by ~112- 627-fold and small sizes could
enable more integration events2.
•No safety considerations or guidelines for LNP enveloped DNA
impurities have been established by regulatory agencies.
•Concerns due to known DNA integration and gene
activation/disruption by SV40 promoter/enhancer sequences.Impurities
1) Regulatory limit guidelines (WHO/FDA/ EMA)
2) Speicher, D. J. et al. Autoimmunity (2025)
•Cancers have been reported in mRNA vaccinated individuals in
temporal association to immunization including (38 case reports and
study of 96 cases of PDAC outcomes vs IgG4):
•High grade sarcoma at injection site (case report).
•Kaposi’s sarcoma (cutaneous and conjunctival reported; 2 cases).
•Non- Hodgkin’s Lymphoma (8 cases reported in one publication).
•Primary Cutaneous Lymphomas (14 cases).
•Marginal Zone B -cell Lymphoma (case report).
•Glioblastoma (2 case reports).
•Gastric and intestinal polyposis (2 case reports).
•IgG4 correlates with poor survival outcomes in PDAC (96 cases).
•Axillary Lymphangioma (case report).
•Multiple Keratoacanthomas (skin cancer; case report).
•Ph+ B -cell ALL (leukemia; case report).
•T-cell ALL (leukemia; case report).
•CMML (leukemia; case report).
•Multiple Myeloma relapse (case report).
•Cardiac Myxoma (2 case reports).COVID Vaccine Safety Issues: Impurities
COVID Vaccine Safety Issues: Impurities
Gaps in Knowledge
•Extent of DNA contamination in current
lots; plasmid biodistribution.
•Genomic integration in tissues or tumors
in vaccinated patients; mechanisms.
•Prevalence of adverse outcomes from
impurities versus extent of contamination.•Multiple vaccinations and Spike persistence.
•Cancer mechanisms.
•Variations in host susceptibilities to
adverse outcomes.
COVID- 19 vaccine safety concerns stem from unexpected
biological activities of mRNA gene therapy platforms, raising
questions about potential pathogenic mechanisms and HRP.
Proactive and modernized safety
surveillance programs including:
Blood- and tissue- based monitoring
Epidemiologic studies
AI-driven analyses using reliable,
standardized datasets
Expanded autopsy programs to clarify causality in serious outcomesPrograms that systematically evaluate COVID -19 vaccine safety
FDA approval policies calibrated to gene therapy –like risks; DNA limits
Stronger pharmaceutical accountability
CDC guidelines ensuring transparent risk disclosure, mitigation strategies, and robust informed consentCOVID Vaccine Summary & Recommendations