Ingredients and mRNA

Ingredients of concern

Ingredients people often ask about. For each one: why it is used, which products in this guide list it, the amount per dose, what official bodies say about its safety, comparison exposures, regulatory history, and any cost reasons the sources give. Quotes are copied from the linked sources. This guide adds no opinion either way. "None found in the sources checked" means we looked and found nothing; it does not mean nothing exists.

Aluminium salts (adjuvants)

Why it is used	Added as an adjuvant, 'a substance added to some vaccines to enhance the immune response'; forms used include aluminum hydroxide, aluminum phosphate, alum and mixed salts. source
UK/US products in this guide that list it	Infanrix hexa Vaxelis Bexsero (MenB) Prevenar 13 / Prevnar 13 (PCV13) REPEVAX (dTaP/IPV pre-school booster) REVAXIS (Td/IPV teenage booster) Gardasil 9 (HPV) Engerix-B (hep B) Recombivax HB (hep B) Daptacel (DTaP) Infanrix (DTaP) Pediarix (DTaP-HepB-IPV) Pentacel (DTaP-IPV/Hib) Kinrix (DTaP-IPV) Quadracel (DTaP-IPV) PedvaxHIB (Hib) Havrix (hep A) Vaqta (hep A) Boostrix (Tdap) Adacel (Tdap) Trumenba (MenB) Vaxneuvance (PCV15) Prevnar 20 / Prevenar 20 (PCV20) Penbraya (MenABCWY)
Amount per dose	Infanrix hexa 0.82 mg Al3+ (0.5 + 0.32 mg); Bexsero 0.5 mg; Gardasil 9 0.5 mg; Revaxis 0.35 mg; Repevax 0.33 mg; Penbraya 0.25 mg; Prevenar 13 / Prevnar 20 0.125 mg; Vaxneuvance 125 mcg (per dose, from each product's leaflet - see Ingredients table). (product leaflets linked in the Ingredients table) US legal limit per dose: 0.85 mg (by assay); 1.14 mg (by calculation); up to 1.25 mg if data show it is safe and necessary. source
Documented safety and toxicity facts	'Aluminum adjuvant containing vaccines have a demonstrated safety profile of over many decades of use and have only uncommonly been associated with severe local reactions.' source
Comparison exposures (diet, water, the body's own production)	'The most common source of exposure to aluminum is from eating food or drinking water.' source The average US adult 'eats about 7-9 mg aluminum per day in their food'; 'Children and adults may be exposed to small amounts of aluminum from vaccinations.' source
Regulatory history	US per-dose aluminium limit set in federal regulation (21 CFR 610.15). source
Cost or commercial reasons given in the sources	None found in the sources checked.

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Thimerosal / thiomersal (ethylmercury)

Why it is used	Preservative to prevent bacterial and fungal growth when needles repeatedly enter a multi-dose vial; also used in manufacture of some vaccines. source US regulation generally requires a preservative in multi-dose vials; FDA cites a 1928 Australian incident (Bundaberg) in which 12 children died after injection from a contaminated multi-dose bottle without preservative. source
UK/US products in this guide that list it	Fluzone Trivalent 2026-27 (flu injection) Flucelvax 2026-27 (flu injection, cell-grown)
Amount per dose	0.01% thimerosal = 50 mcg thimerosal, about 25 mcg mercury per 0.5 mL dose. 2026-27 US labels: Fluzone multi-dose vial 25 mcg mercury per 0.5 mL; Flucelvax multi-dose vial 25 mcg. Single-dose syringes of these brands contain none. source source 2 FDA table: Afluria multi-dose 24.5 mcg mercury per 0.5 mL. source
Documented safety and toxicity facts	Metabolised to ethylmercury and thiosalicylate; FDA says ethylmercury 'should be distinguished from methylmercury' (the type in fish), which 'at high exposure levels... can be toxic'. FDA's 1999 review 'found no evidence of harm... other than local hypersensitivity reactions'. source FDA 1999 review: depending on formulations and infant weight, 'some infants could have been exposed to cumulative levels of mercury during the first six months of life that exceeded Environmental Protection Agency (EPA) recommended guidelines for safe intake of methylmercury'. source WHO's advisory committee: 'no evidence to suggest that the amount of thiomersal used in vaccines poses a health risk'. source
Comparison exposures (diet, water, the body's own production)	FDA: 25 mcg mercury per 0.5 mL dose is 'roughly the same amount of elemental mercury contained in a 3 ounce can of tuna fish'. source
Regulatory history	US: 1 July 1999 FDA asked all manufacturers for plans to remove thimerosal, as 'a precautionary measure'. By 2001, except flu vaccines, it was 'removed from or reduced in all vaccines routinely recommended for children 6 years of age and under'. source source 2 UK: Department of Health letter of 10 Aug 2004 - from 27 Sept 2004 new childhood vaccines (Pediacel, Repevax, Revaxis) were introduced; 'there is no thiomersal in the new vaccines'. source US: July 2025 the HHS Secretary adopted an ACIP recommendation that children, pregnant women and adults receive only single-dose, thimerosal-free flu vaccines. source The 2026-27 FDA labels for Fluzone and Flucelvax still describe a multi-dose vial containing thimerosal. source source 2
Cost or commercial reasons given in the sources	WHO: 'Multi-dose vials are used in many countries because they require less storage space in the cold-chain and lead to less wastage, both of which have a significant impact on programme costs.' 'Alternatives would incur significant costs for development and regulatory approval, thereby limiting the ability to offer affordable vaccines.' source FDA: multi-dose vials 'help facilitate immunization campaigns in the United States and globally'. source

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Formaldehyde

Why it is used	Used 'to inactivate viruses so that they don't cause disease... and to detoxify bacterial toxins'; residual amounts may remain. source
UK/US products in this guide that list it	Infanrix hexa Vaxelis REPEVAX (dTaP/IPV pre-school booster) REVAXIS (Td/IPV teenage booster) MenQuadfi (MenACWY) Recombivax HB (hep B) Daptacel (DTaP) Infanrix (DTaP) Pediarix (DTaP-HepB-IPV) Pentacel (DTaP-IPV/Hib) Kinrix (DTaP-IPV) Quadracel (DTaP-IPV) ActHIB (Hib) Hiberix (Hib) IPOL (polio, IPV) Havrix (hep A) Vaqta (hep A) Boostrix (Tdap) Adacel (Tdap) Menveo (MenACWY) Fluzone Trivalent 2026-27 (flu injection) Fluarix 2026-27 (flu injection) FluLaval 2026-27 (flu injection)
Amount per dose	2026-27 flu labels: Fluzone up to 100 mcg per 0.5 mL; FluLaval up to 25 mcg; Fluarix up to 5 mcg. source source 2
Documented safety and toxicity facts	'Excessive exposure to formaldehyde may cause cancer, but... the highest risk is from the air when formaldehyde is inhaled... There is no evidence linking cancer to infrequent exposure to tiny amounts of formaldehyde via injection as occurs with vaccines.' source
Comparison exposures (diet, water, the body's own production)	The body makes formaldehyde naturally; 'for a newborn of average weight of 6 - 8 pounds, the amount of formaldehyde in their body is 50-70 times higher than the upper amount that they could receive from a single dose of a vaccine or from vaccines administered over time'. source
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Polysorbate 80

Why it is used	An emulsifier that 'helps ingredients mix together and keep them from separating' (FDA, describing the AS03 adjuvant). source
UK/US products in this guide that list it	Vaxelis Prevenar 13 / Prevnar 13 (PCV13) REPEVAX (dTaP/IPV pre-school booster) REVAXIS (Td/IPV teenage booster) Gardasil 9 (HPV) Abrysvo (RSV, given in pregnancy) RotaTeq (rotavirus, oral) Infanrix (DTaP) Pediarix (DTaP-HepB-IPV) Pentacel (DTaP-IPV/Hib) Kinrix (DTaP-IPV) Quadracel (DTaP-IPV) Boostrix (Tdap) Trumenba (MenB) Fluarix 2026-27 (flu injection) FluLaval 2026-27 (flu injection) Flucelvax 2026-27 (flu injection, cell-grown) Prevnar 20 / Prevenar 20 (PCV20) Penbraya (MenABCWY) Beyfortus (nirsevimab) - monoclonal antibody, not a vaccine Enflonsia (clesrovimab) - monoclonal antibody, not a vaccine
Amount per dose	Flucelvax up to 1,125 mcg; FluLaval up to 665 mcg; Fluarix up to 415 mcg per dose (2026-27 labels). Enflonsia 0.14 mg; Penbraya 0.018 mg. source source 2 Infant vaccines: Prevnar 20 100 mcg per dose; Pediarix up to 100 mcg per dose. source source 2
Documented safety and toxicity facts	Published LD50 (ChemIDplus/RTECS): intravenous rat 1,790 mg/kg; intravenous mouse 4,500 mg/kg; intraperitoneal rat 6,804 mg/kg; intraperitoneal mouse 7,600 mg/kg; oral mouse 25,000 mg/kg; oral rat 34.5 mL/kg. Lowest reported lethal dose (LDLo), intravenous dog and cat: 500 mg/kg. No intramuscular or subcutaneous LD50 found. source EFSA reports that 'The acute toxicity is very low' and that there is 'no concern regarding genotoxicity, carcinogenicity or developmental toxicity' (food-additive review). source Guide's own arithmetic Scaled to a 5 kg baby: intravenous rat LD50 = 8,950 mg; lowest lethal dose in dogs and cats (intravenous) = 2,500 mg. One infant dose of Prevnar 20 contains 0.1 mg: 89,500 times less than the rat figure (0.0011%) and 25,000 times less than the dog/cat figure (0.004%). The largest amount listed here, Flucelvax 1.125 mg (given from 6 months), is about 8,000 times less than the rat figure (0.013%) and about 2,200 times less than the dog/cat figure (0.045%). LD50 is the single dose that killed half of the test animals; it measures acute lethality only, not chronic, allergic or cumulative effects, and scaling an animal result to a baby by body weight is a simplification. Route matters: most vaccines are injected into muscle, so injected (intravenous, subcutaneous) values are more relevant than oral ones. source source 2
Comparison exposures (diet, water, the body's own production)	EFSA (2015) keeps a group acceptable daily intake (ADI) of 25 mg per kg body weight per day for polysorbates in food (oral), based on a no-observed-adverse-effect level (NOAEL) of 2,500 mg/kg/day in rats. source Guide's own arithmetic For a 5 kg baby the ADI equals 125 mg a day by mouth; one 0.1 mg infant dose is 0.08% of one day's ADI, and 1.125 mg (Flucelvax) is 0.9%. The ADI is for food eaten every day, not for injection. source
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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2-Phenoxyethanol

Why it is used	Preservative; 'sometimes used in cosmetics and antiseptics'. FDA lists it in one available US vaccine, IPOL, at 0.5%. source
UK/US products in this guide that list it	REPEVAX (dTaP/IPV pre-school booster) REVAXIS (Td/IPV teenage booster) Daptacel (DTaP) Pentacel (DTaP-IPV/Hib) Quadracel (DTaP-IPV) IPOL (polio, IPV) Adacel (Tdap)
Amount per dose	IPOL: 0.5% concentration. source
Documented safety and toxicity facts	EU scientific committee 'considers 2-phenoxyethanol safe for use as a preservative with a maximum concentration of 1.0 %' in cosmetics. source
Comparison exposures (diet, water, the body's own production)	Cosmetics limit reviewed by the EU committee: 1.0%; IPOL contains 0.5%. source source 2
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Residual egg protein (ovalbumin)

Why it is used	Some flu viruses and the measles and mumps components of MMR are grown in hens' eggs or chick-embryo cells. source source 2
UK/US products in this guide that list it	ProQuad (MMRV) Priorix-Tetra (MMRV) Fluenz Tetra (2020) / Fluenz (current, nasal flu) Fluzone Trivalent 2026-27 (flu injection) Fluarix 2026-27 (flu injection) FluLaval 2026-27 (flu injection) FluMist 2026-27 (nasal spray, live) Priorix (MMR, US licence 2022)
Amount per dose	Fluarix up to 0.05 mcg ovalbumin; FluLaval up to 0.3 mcg (2026-27 labels). Flucelvax and Flublok contain no egg protein. source source 2
Documented safety and toxicity facts	Pink Book: 'MMR vaccine may be administered to egg-allergic persons without prior routine skin testing or the use of special protocols.' source
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	A flu vaccine 'not requiring isolation or growth in hen's eggs was licensed in 2013' (Flublok). source
Cost or commercial reasons given in the sources	None found in the sources checked.

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Residual yeast protein

Why it is used	Hepatitis B and HPV vaccine proteins are made in baker's yeast (Saccharomyces cerevisiae). source source 2
UK/US products in this guide that list it	Vaxelis Gardasil 9 (HPV) Engerix-B (hep B) Recombivax HB (hep B) Pediarix (DTaP-HepB-IPV)
Amount per dose	Amount per dose not stated in the sources compiled.
Documented safety and toxicity facts	'History of hypersensitivity to yeast' is a contraindication to hep B vaccine. In 2011 the Institute of Medicine concluded 'the evidence convincingly supports a causal relationship between HepB vaccine and anaphylaxis in yeast-sensitive persons'. source
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Gelatin (usually porcine)

Why it is used	Stabiliser; protects the vaccine during freeze-drying. FDA: such proteins 'are encountered in everyday life in the diet'. source
UK/US products in this guide that list it	ProQuad (MMRV) Fluenz Tetra (2020) / Fluenz (current, nasal flu) M-M-R II (MMR) Varivax (chickenpox)
Amount per dose	Amount per dose not stated in the sources compiled.
Documented safety and toxicity facts	Pink Book lists MMR and varicella vaccines as containing gelatin; severe allergy to a vaccine component is a contraindication. source source 2
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Monosodium glutamate (MSG)

Why it is used	Stabiliser ('the monosodium salt of glutamic acid'). source
UK/US products in this guide that list it	ProQuad (MMRV) Fluenz Tetra (2020) / Fluenz (current, nasal flu) M-M-R II (MMR) Varivax (chickenpox)
Amount per dose	Amount per dose not stated in the sources compiled.
Documented safety and toxicity facts	FDA considers MSG in food 'generally recognized as safe' (GRAS); it has received reports of symptoms such as headache and nausea after eating foods containing MSG. source
Comparison exposures (diet, water, the body's own production)	'An average adult consumes approximately 13 grams of glutamate each day from the protein in food, while intake of added MSG is estimated at around 0.55 grams per day.' source
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Neomycin and other antibiotics

Why it is used	Used 'to help prevent bacterial contamination during manufacturing'; reduced to very small or undetectable amounts. source
UK/US products in this guide that list it	Infanrix hexa Vaxelis Bexsero (MenB) ProQuad (MMRV) Priorix-Tetra (MMRV) REPEVAX (dTaP/IPV pre-school booster) Fluenz Tetra (2020) / Fluenz (current, nasal flu) Pediarix (DTaP-HepB-IPV) Pentacel (DTaP-IPV/Hib) Kinrix (DTaP-IPV) Quadracel (DTaP-IPV) IPOL (polio, IPV) M-M-R II (MMR) Varivax (chickenpox) Havrix (hep A) Vaqta (hep A) Fluarix 2026-27 (flu injection) Priorix (MMR, US licence 2022)
Amount per dose	Priorix (US) neomycin up to 25 mcg per dose; Fluarix gentamicin up to 0.15 mcg. source
Documented safety and toxicity facts	'Antibiotics most likely to cause severe allergic reactions (e.g., penicillins, cephalosporins and sulfa drugs) are not used in vaccine production'; 'the very small amounts... have not been clearly associated with severe allergic reactions'. source
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Residual cell-line DNA and protein (MRC-5, WI-38, Vero, MDCK, CHO)

Why it is used	Viruses for some vaccines are grown in cells: rubella in WI-38 human diploid lung fibroblasts; varicella passed through MRC-5 human diploid cells; polio (IPV) in monkey kidney (Vero) cells. source source 2 WI-38 and MRC-5 are listed by the Coriell repository as diploid human fetal lung fibroblast cell strains (MRC-5 'from Britain'). source
UK/US products in this guide that list it	ProQuad (MMRV) Priorix-Tetra (MMRV) REPEVAX (dTaP/IPV pre-school booster) REVAXIS (Td/IPV teenage booster) M-M-R II (MMR) Varivax (chickenpox) Havrix (hep A) Flucelvax 2026-27 (flu injection, cell-grown) Priorix (MMR, US licence 2022) Enflonsia (clesrovimab) - monoclonal antibody, not a vaccine
Amount per dose	Flucelvax (dog-kidney MDCK cells): up to 10 ng cell DNA and up to 21.6 mcg cell protein per dose (2026-27 label). Amounts for MRC-5/WI-38 vaccines not stated in sources compiled. source
Documented safety and toxicity facts	No LD50 published: residual cell DNA and protein are not tested for a lethal dose. (none found in ChemIDplus, PubChem or ECHA) WHO (2013) reports that its earlier recommendation 'sets the upper limit of rcDNA [residual cell DNA] at 10 ng per parenteral dose', and that DNA from primary cells and diploid cell lines (such as MRC-5 and WI-38) 'has not been (and is not) considered to pose any significant risk'; the theoretical concern is with continuous cell lines that grow indefinitely (such as Vero and MDCK). source Guide's own arithmetic Flucelvax's stated maximum, 10 ng of MDCK cell DNA per dose, equals the WHO upper limit of 10 ng. source source 2
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Glutaraldehyde

Why it is used	Listed as a manufacturing residual in several DTaP-containing vaccines (CDC 2020 excipient table). source
UK/US products in this guide that list it	Vaxelis REPEVAX (dTaP/IPV pre-school booster) Daptacel (DTaP) Pentacel (DTaP-IPV/Hib) Quadracel (DTaP-IPV) Adacel (Tdap)
Amount per dose	Less than 50 ng (0.00005 mg) residual glutaraldehyde per 0.5 mL dose in Daptacel and Pentacel (US labels); 50 ng or less in Vaxelis. source source 2 Pentacel label: '<50 ng residual glutaraldehyde'. source
Documented safety and toxicity facts	Published LD50 (ChemIDplus/RTECS): intravenous rat 9.8 mg/kg; intravenous mouse 15.4 mg/kg; intraperitoneal rat 17.9 mg/kg; intraperitoneal mouse 13.9 mg/kg; subcutaneous rat more than 750 mg/kg; subcutaneous mouse more than 590 mg/kg; oral rat 134 mg/kg (PubChem/HSDB also lists 154-315 mg/kg in other rat studies). No intramuscular LD50 found. source source 2 Guide's own arithmetic Scaled to a 5 kg baby: intravenous rat LD50 = 49 mg; subcutaneous rat = more than 3,750 mg; oral rat = 670 mg. One dose contains less than 0.00005 mg: at least 980,000 times less than the intravenous rat figure (about 0.0001% or less), and about 13 million times less than the oral figure. LD50 is the single dose that killed half of the test animals; it measures acute lethality only, not chronic, allergic or cumulative effects, and scaling an animal result to a baby by body weight is a simplification. Route matters: most vaccines are injected into muscle, so injected (intravenous, subcutaneous) values are more relevant than oral ones. source source 2
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Natural rubber latex (packaging)

Why it is used	Not an ingredient: some syringe tip caps or vial stoppers are made with natural rubber latex. Priorix (US): the diluent syringe tip caps 'contain natural rubber latex'. source
UK/US products in this guide that list it	Priorix (MMR, US licence 2022)
Amount per dose	Not applicable (packaging).
Documented safety and toxicity facts	Pink Book: some hepatitis B and A vaccine presentations contain latex; a 2-valent HPV vaccine 'should not be used in persons with an anaphylactic allergy to latex'. source source 2 FDA discourages 'latex-free' labelling because 'it is not possible to reliably assure that there is an absence of the allergens'. source
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	FDA labelling guidance on latex statements issued December 2014. source
Cost or commercial reasons given in the sources	None found in the sources checked.

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PEG-lipids and lipid nanoparticles (mRNA vaccines)

Why it is used	The mRNA is packaged in lipid particles; Comirnaty lists ALC-0315, ALC-0159 (a polyethylene glycol-2000 lipid), DSPC and cholesterol. source
UK/US products in this guide that list it	Comirnaty (Pfizer-BioNTech COVID-19, mRNA) Spikevax (Moderna COVID-19, mRNA)
Amount per dose	Amounts per dose not listed in the SmPC excipient section. source
Documented safety and toxicity facts	US, 14-23 Dec 2020: 21 anaphylaxis cases after 1,893,360 first doses of Pfizer-BioNTech (11.1 per million); 17 had a history of allergies; all 20 with follow-up recovered or were discharged. (The report does not attribute the reactions to a specific ingredient in the abstract.) source
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	Formulation changed from phosphate-buffered saline to trometamol buffer (lipids unchanged) - see Ingredients table.
Cost or commercial reasons given in the sources	None found in the sources checked.

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Other commonly flagged: fetal bovine serum, porcine circovirus DNA

Why it is used	Fetal bovine serum: when viruses are grown in cells, 'these cells need a source of nutrition, which in some instances may be provided by fetal bovine serum'. source Porcine circovirus: CDC's 2020 table notes PCV-1 is present in Rotarix and PCV-1/PCV-2 DNA in RotaTeq, 'not known to cause disease in humans'. source
UK/US products in this guide that list it	Rotarix (rotavirus, oral) RotaTeq (rotavirus, oral) M-M-R II (MMR) Varivax (chickenpox)
Amount per dose	Not stated in the sources compiled.
Documented safety and toxicity facts	None found in the sources checked.
Comparison exposures (diet, water, the body's own production)	None found in the sources checked.
Regulatory history	None found in the sources checked.
Cost or commercial reasons given in the sources	None found in the sources checked.

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mRNA vaccines, and mRNA and DNA

mRNA vaccines give the body's cells a genetic message (messenger RNA) to make one protein from the germ, so the immune system learns to recognise it. Other vaccine types use a weakened live germ, a killed germ, a piece of the germ, or an inactivated toxin. vaccine types (HHS)

mRNA products licensed in the UK or US

• None of these mRNA products is on the routine childhood schedule in the UK. No viral-vector vaccine is among the products in this guide. (checked against the schedules in this guide, 22 Oct 2026)

mRNA and DNA: what the sources say

Official statements, independent studies and their stated limits, quoted from the linked sources. This guide takes no position.

The official position

• CDC: 'COVID-19 vaccines do not change or interact with your DNA in any way... The genetic material delivered by mRNA vaccines never enters the nucleus of your cells, which is where your DNA is kept.' source
• UK Green Book: 'mRNA is a natural component of the body, does not enter the nucleus and is processed entirely in the cytoplasm.' source
• FDA (Dec 2023): 'it is quite implausible that the residual small DNA fragments located in the cytosol could find their way into the nucleus through the nuclear membrane present in intact cells and then be incorporated into chromosomal DNA.' FDA adds that animal studies and data from 'hundreds of millions of individuals' show no evidence of genotoxicity (damage to DNA). source

Leftover (residual) plasmid DNA and the SV40 fragment

• How it gets there (FDA): the mRNA is made from a DNA template, which is then broken up with an enzyme (DNAse). The limit for leftover DNA fragments is 'less than three orders of magnitude lower than the quantity of the RNA dose by weight', checked by a validated qPCR test. source
• McKernan et al. (2023, preprint, not peer-reviewed) tested 4 bivalent vials (2 Pfizer, 2 Moderna) and report 'DNA contamination that exceeds the European Medicines Agency (EMA) 330ng/mg requirement and the FDAs 10ng/dose requirements'. McKernan and Dr Phillip Buckhaults then publicly raised the SV40 promoter/enhancer sequence in Pfizer's plasmid (as Health Canada later noted). source source 2
• Speicher, Rose and McKernan (2025, peer-reviewed, 32 vials from 16 lots in Ontario): by fluorometry, total DNA was above the regulatory limit in all vials; by qPCR (the regulators' method) 'all Moderna vials were within the regulatory limit, but 2/6 Pfizer lots (3 vials) exceeded the regulatory limit for the SV40 promoter-enhancer-ori by 2-fold'. The SV40 sequence was found only in Pfizer vials. source
• Kaiser et al. (2025, peer-reviewed, Frankfurt) tried to reproduce such claims with other methods and found DNA:RNA ratios of 1:1000, 'consistent with the specifications'. They say earlier high readings were 'a consequence of extraordinary high RNA and lipid concentrations' interfering with the test. source
• Health Canada: 'Although the full DNA sequence of the Pfizer plasmid was provided at the time of initial filing, the sponsor did not specifically identify the SV40 sequence.' source
• Health Canada: the vaccine contains no SV40 virus, only residual fragments of the SV40 promoter-enhancer, under 'strict quality limits'; 'Any claims that the presence of the SV40 promoter enhancer sequence is linked to an increased risk of cancer are unfounded.' source
• FDA: 'No SV40 proteins are encoded for or are present in the vaccines.' FDA says the 2007 plasmid-DNA guidance some critics cite 'was developed for DNA vaccines themselves, not for DNA as a contaminant in other vaccines'. source
• Limits of the evidence: the independent studies tested small numbers of vials (4 and 32). Speicher et al. argue that limits should consider 'increased LNP transfection efficiency' (DNA carried inside lipid nanoparticles gets into cells more easily) and 'cumulative dosing'. (summary by this guide of the sources above)

Aldén et al. 2022: reverse transcription in a lab dish

• Swedish researchers exposed a human liver cancer cell line (Huh7) to the Pfizer vaccine in a lab dish. They report that 'BNT162b2 mRNA is reverse transcribed intracellularly into DNA in as fast as 6 h', with changes in LINE-1 (the body's own enzyme that can copy RNA into DNA). source
• Limits the authors state: 'At this stage, we do not know if DNA reverse transcribed from BNT162b2 is integrated into the cell genome.' 'The cell model that we used in this study is a carcinoma cell line, with active DNA replication which differs from non-dividing somatic cells.' They call for further work 'both in vitro and in vivo', including 'tissues from human subjects who received BNT162b2'. A published comment (Merchant 2022) followed in the same journal. source source 2

Has anyone shown integration into human DNA in vaccinated people?

• One 2025 case report (one 31-year-old patient with bladder cancer, published in an Indian journal) claims 'the first documented evidence of genomic integration'. The evidence is a single 20-base sequence read in tumour DNA from the blood. The authors write that 'causality cannot be established from a single case' and call for 'orthogonal validation with long-read sequencing'. source
• No study has independently confirmed vaccine DNA built into the DNA of vaccinated people. Apart from the single case report above, no peer-reviewed study was found claiming this. No regulator (FDA, MHRA, EMA, Health Canada) reports such a finding. (search done 22 Oct 2026)

Ingredients by product

Vaccine type filter: All products mRNA only Not mRNA

Ingredients other than the active part (the germ or toxin component). Taken from archived copies of official leaflets dated 2020 or earlier where one exists, with differences from today's version noted. Products with no archive from 2020 or earlier are marked. Vaccine type uses the HHS categories definitions; each product's type is as stated in its official leaflet linked in the right-hand column.