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Plain English

Two lists: what the ingredients are, and what the technical words in the labels mean. These are definitions. They are not judgements about any product.

Ingredients, residues and materials

Where a label names an ingredient, this is what that thing is. The reason it is in the vaccine is given where the label states it. The brand names and the full lists are on each product page.

acetic acid
The acid in vinegar, used to adjust the acidity.
adipate
A buffer salt used to hold the acidity steady.
adjuvant
An added ingredient that makes the immune system react more strongly to the vaccine.
aluminium
An aluminium salt. It is an adjuvant: it makes the immune system respond more strongly to the vaccine. Aluminium in vaccines has been used since the 1930s.
amino acids
The building blocks of protein, present here as nutrients for the cells grown during manufacture.
arginine hydrochloride
Arginine is an amino acid, one of the building blocks of protein. Here it keeps the liquid at a steady acidity.
as01
AS01 is GSK's adjuvant system: a mix of liposomes (tiny fat bubbles), MPL and QS-21. Adjuvants are added to make the immune response stronger.
as03
AS03 is an adjuvant: squalene (a natural oil), vitamin E and polysorbate 80, mixed into a milky emulsion to strengthen the immune response.
as04
AS04 is an adjuvant: an aluminium salt combined with MPL, used to strengthen the immune response.
attenuated
Weakened on purpose so the organism cannot cause the disease in a healthy person.
borax
Also called sodium tetraborate (E285), a mineral salt used to hold the acidity steady.
crm197
A carrier protein made from a modified diphtheria toxin. Harmless in this form, and used to carry a sugar antigen so the immune system notices it.
dioleoyl phosphatidylcholine
Lecithin (E322), a fat from soy or egg, used to form the tiny fat bubbles (liposomes) that carry the adjuvant.
diphtheria toxoid
A diphtheria toxin that has been treated so it can no longer cause disease but still trains the immune system.
dipotassium phosphate
A phosphate buffer, used to hold the liquid at a steady acidity.
dtpa
A chelating agent, which grabs and holds trace metal ions that would otherwise break the vaccine down.
e. coli
A common gut bacterium used in the laboratory as a factory to make proteins or DNA. The bacterium itself is not in the finished vaccine.
egg protein
Protein from hens' eggs, left over from growing the virus. It is why a severe egg allergy is a contraindication.
ethanol
Alcohol, used as a solvent and to help inactivate viruses during manufacture.
formaldehyde
A chemical used to inactivate (kill) viruses or bacteria during manufacture. It is then removed, and only trace amounts can remain.
gelatin
A protein made by boiling animal collagen. Porcine gelatin comes from pig skin or bone; hydrolysed gelatin is broken into smaller pieces. Used as a stabiliser, and it is the reason some people with a gelatin allergy cannot have this vaccine.
genetically modified
Made using genetic engineering.
gentamicin
An antibiotic used during manufacture to stop bacteria growing. Traces may remain, which is why a gentamicin allergy is a contraindication.
glucose
A simple sugar, used as a stabiliser.
hanks
A standard salt solution used to grow cells in the laboratory.
histidine
An amino acid, one of the building blocks of protein. Used to keep the liquid at a stable acidity.
hydrochloric acid
A strong acid used in tiny amounts to adjust the acidity of the liquid.
kanamycin
An antibiotic used during manufacture. Traces may remain, which is why a kanamycin allergy is a contraindication.
lactose
Milk sugar, used as a stabiliser and bulking agent.
mannitol
A sugar alcohol used as a stabiliser and bulking agent, so the dried powder forms a proper cake.
medium 199
A standard laboratory nutrient mixture (salts, vitamins, amino acids, sugars) that cells are grown in. Its residues are diluted out almost entirely.
mineral salts
Simple salts (sodium, potassium, calcium and similar) used to keep the liquid balanced.
minimum essential medium
A standard laboratory nutrient mixture that cells are grown in.
monophosphoryl
MPL, a purified piece of bacterial cell wall, used as an adjuvant to strengthen the immune response.
monosodium glutamate
The flavour enhancer known as MSG, a salt of the amino acid glutamate. Here it acts as a stabiliser, not a flavour.
neisseria meningitidis
The bacterium that causes meningococcal disease. The vaccine uses purified proteins from it, not the live bacterium.
neomycin
An antibiotic used during manufacture to stop bacteria growing. Traces may remain, which is why a neomycin allergy is a contraindication.
nz98/254
The laboratory reference name of the bacterial strain the proteins were copied from.
outer membrane vesicles
Small packages pinched off the outer coat of the bacterium. They are purified parts of the germ, not the live bacterium.
ovalbumin
The main protein in egg white. It is left over from growing the virus in hens' eggs, and it is why a severe egg allergy is a contraindication.
para-aminobenzoic acid
A vitamin-like nutrient, sometimes called PABA, used to grow the cells.
phenol
A preservative that stops bacteria growing. Also used in some antiseptics. It is toxic in large amounts, which is why only trace quantities are used.
phenol red
A pH indicator. It is there so the liquid changes colour if the acidity drifts.
phenoxyethanol
2-phenoxyethanol, a preservative that stops bacteria growing in a multi-dose container. Also used in cosmetics.
phenylalanine
An amino acid. People with the inherited condition phenylketonuria (PKU) have to limit it, which is why it is declared.
polymyxin
An antibiotic used during manufacture. Traces may remain, which is why a polymyxin allergy is a contraindication.
polysorbate 80
An emulsifier (E433), also used in some foods and cosmetics. It stops the ingredients separating.
pora p1.4
A protein from the outer coat of the meningococcal bacterium.
potassium chloride
A mineral salt, similar to salt, used to balance the liquid.
potassium phosphate
A phosphate buffer, used to hold the liquid at a steady acidity.
qs-21
A substance extracted from the soap bark tree, used as an adjuvant.
recombinant
Made by genetic engineering: the gene for one piece of the germ is put into a laboratory cell or bacterium, which then makes that piece.
saponin
A plant extract used as an adjuvant.
sodium acetate
A buffer (E262), used to hold the liquid at a steady acidity.
sodium bicarbonate
Bicarbonate of soda, used to hold the acidity steady.
sodium chloride
Salt. Used to keep the liquid at the same saltiness as the body.
sodium glutamate
A salt of the amino acid glutamate (MSG is the monosodium form). Here it acts as a stabiliser.
sodium hydroxide
An alkali used in tiny amounts to adjust the acidity of the liquid.
sodium phosphate
A phosphate buffer, used to hold the liquid at a steady acidity.
sorbitol
A sugar alcohol used as a stabiliser and to give the liquid bulk. Also found in sugar-free food.
squalene
A natural oil found in the human body, in plants and in shark liver. Used as an adjuvant to strengthen the immune response.
streptococcus pneumoniae
The bacterium the pneumococcal vaccines protect against. The vaccine uses its purified outer sugars, not the live bacterium.
streptomycin
An antibiotic used during manufacture. Traces may remain, which is why a streptomycin allergy is a contraindication.
succinic acid
An acid used to hold the liquid at a steady acidity.
sucrose
Sugar. Used as a stabiliser so the vaccine keeps its potency in storage.
tetanus toxoid
A tetanus toxin that has been treated so it can no longer cause disease but still trains the immune system.
tocopherol
Vitamin E, used here as part of an adjuvant mixture.
trometamol
A buffering agent, used to hold the liquid at a steady acidity so the vaccine does not degrade.
urea
A waste product the body makes anyway, used here in a small amount as a stabiliser.
vero
VERO cells: a laboratory-grown line of kidney cells originally taken from an African green monkey in 1962. Cells, not animal tissue, and they are not present in the finished vaccine.
vitamins
Vitamins added as nutrients for the cells grown during manufacture.
water for injections
Purified water to the standard used for injected medicines. It is the liquid the other ingredients are dissolved in.
yeast
Used in the laboratory to produce proteins. Traces can remain, which is why a yeast allergy can be a problem.

Words the labels use

Regulatory documents are written for healthcare professionals. This is what the recurring terms mean, including the frequency bands the labels use to describe how often something was reported.

active-controlled
A trial where the comparison group gets another real vaccine, not a dummy.
adjuvant
An added ingredient that makes the immune system react more strongly to a vaccine.
anaphylaxis
A severe, sudden allergic reaction that can make breathing difficult and needs urgent medical treatment.
antigen
The part of a germ that the immune system recognises and remembers.
apnoea
A pause in breathing.
arthralgia
Joint pain.
attenuated
Weakened on purpose so the virus or bacterium can no longer cause the disease in a healthy person.
blinded
A trial where people do not know which treatment they received, to avoid bias.
common
In the label's frequency scale, this means it happened in up to 1 in 10 people studied.
confidence interval
The range of results within which the true figure is likely to sit. A wide range means the result is less certain.
conjugate
A design where a sugar from a germ is attached to a carrier protein, so the immune system responds properly.
contraindicated
A situation where the medicine should not be given at all.
correlate of protection
A lab measurement that is thought to predict whether someone is actually protected. It is a stand-in, not proof.
could not be made
The evidence was not strong or consistent enough for the company to draw a conclusion.
do not administer
The label instructs that it must not be given.
effectiveness
How well it works in ordinary use in the real world.
efficacy
How well it works in the controlled conditions of a trial.
encephalitis
Inflammation of the brain.
epistaxis
A nosebleed.
excipient
Any ingredient in a medicine other than the active substance.
febrile convulsion
A fit caused by a high temperature, most common in young children. Usually brief and not harmful in itself.
fertilised hens
The virus is grown inside hens' eggs that have been fertilised.
ffu
Fluorescent focus units: a laboratory count of how much live virus is in the dose.
genetically modified
Made using genetic engineering.
geometric mean
An average used for antibody levels, because those vary over a huge range.
gmo
Genetically modified organism - a living thing whose genes have been altered in the laboratory.
gmt
Geometric mean titre: the average antibody level in a group of people.
guillain-barre
A rare condition where the immune system attacks nerves, causing weakness or paralysis. Most people recover, but slowly.
hai
Haemagglutination inhibition: a lab test that measures antibodies by seeing how well they stop flu virus sticking to red blood cells.
has not been evaluated
It has not been tested or measured in this group or situation.
has not been studied
No trial has been run for this group or this situation.
has not yet been established
There is not yet enough evidence to state a conclusion.
have not been studied
No trials have been run for this group or this situation.
healthy chicken flocks
The eggs used to grow the virus came from chickens kept for that purpose, tested for disease.
hen
A female chicken. The virus is grown inside hens' eggs that have been fertilised.
hypersensitivity
An allergic-type reaction, from a mild rash up to a severe reaction.
immunocompromised
Having a weakened immune system, from illness or from medicines such as chemotherapy.
immunogenicity
How strongly the vaccine provokes an immune response. It is measured in the blood, not by how many people avoided the illness.
immunological correlate
A lab measurement used as a stand-in for protection.
immunosuppressive
A medicine or treatment that dampens the immune system.
in vitro
Done in a laboratory dish or test tube, not in a living body.
inactivated
Killed. The organism cannot replicate at all.
insufficient
Not enough to draw a conclusion from.
intussusception
A rare bowel blockage, mostly in babies, where one part of the gut folds into the next. It is a medical emergency.
limited data
Only a small amount of information exists on this point, so firmer conclusions cannot be drawn.
limited experience
The product has been used only a small number of times in this group.
limited information
Only a small amount of information exists on this point.
live attenuated
A vaccine containing a weakened but still living organism. It can still replicate in the body and, with a nasal flu vaccine, be passed on.
mah
Marketing Authorisation Holder: the company that holds the licence for the product.
malaise
Feeling generally unwell and lacking energy.
meningitis
Inflammation of the lining around the brain and spinal cord.
mrna
Messenger RNA: temporary instructions telling cells to make one protein. It does not enter the cell's own DNA.
myalgia
Muscle aches.
myocarditis
Inflammation of the heart muscle.
neurovirulence
The ability to damage nerve tissue.
no conclusion
The evidence did not allow the company to reach a verdict either way.
no data
The label is stating that no study has measured this. It is a statement about what was tested, not about what was found.
no information
The label is stating that it has nothing to report on this point.
no studies
No research has been done on this point.
non-clinical
Lab and animal studies, done before or alongside human trials.
non-inferiority
A trial designed to show a new vaccine is not worse than an existing one, rather than that it is better.
not applicable
This measurement does not apply to this kind of product.
not been established
There is not yet enough evidence to state a conclusion.
not been evaluated
It has not been tested or measured in this group or situation.
not been studied
No trial has been run for this group or this situation.
not known
The label's lowest band: the number of cases is too small, or the reporting too patchy, to work out how often it happens.
not recommended
The manufacturer advises against it. This is weaker than 'contraindicated', which means it must not be given.
off-label
Use outside what the product is formally licensed for.
pharmacovigilance
The system for collecting and acting on reports of side effects after a medicine is in use.
pil
Patient Information Leaflet: the leaflet inside the pack.
placebo
A dummy injection with no active ingredient, used as a comparison group in a trial.
placebo-controlled
A trial where one group gets a dummy instead of the vaccine, so the two can be compared.
posology
The dose, and how and when it is given.
post-marketing
After the product went on the market and was given to the public, as opposed to during the original clinical trials.
psur
Periodic Safety Update Report: a safety report the company must send the regulator at set intervals.
pyrexia
A fever.
randomised
A trial where people are assigned to groups by chance.
rare
In the label's frequency scale, this means it happened in up to 1 in 1,000 people studied.
recombinant
Made by genetic engineering: the gene for one piece of a germ is put into a lab cell or bacterium, which then makes that piece.
reproductive toxicity
Harm to fertility or to an unborn baby.
reverse genetic
A laboratory technique for building a virus from copied genetic material.
reye
Reye's syndrome: a rare and serious illness affecting the brain and liver that can follow a viral infection in children given aspirin-type medicines.
rhinorrhoea
A runny nose.
rmp
Risk Management Plan: the company's written plan for tracking and limiting the risks of the product.
seroconversion
A rise in antibodies after vaccination, measured in the blood.
seroprotection
Having an antibody level above a set threshold, taken as a sign of protection.
shedding
The vaccine organism being released from the body, for example in nasal mucus, and possibly passing to other people.
should not be given
The label says the product should not be given in this situation.
should not be used
The label says the product should not be given in this situation.
smpc
Summary of Product Characteristics: the technical document written for healthcare professionals that this site quotes from.
surrogate
A stand-in measurement used instead of the outcome you actually care about.
teratogenic
Causing birth defects.
thrombocytopenia
A low platelet count, which makes bruising and bleeding easier.
titre
The measured level of antibodies in a blood sample.
toxoid
A bacterial toxin that has been treated so it can no longer cause harm but still trains the immune system.
transmission
Passing something from one person to another.
uncertain
The evidence does not settle the question.
uncommon
In the label's frequency scale, this means it happened in up to 1 in 100 people studied.
vector
A harmless virus or piece of DNA used to carry genetic instructions into cells.
very common
In the label's frequency scale, this means it happened in more than 1 in 10 people studied.
very rare
In the label's frequency scale, this means it happened in up to 1 in 10,000 people. Often these are reports sent in after a vaccine is in use rather than findings from a formal study.
wide confidence interval
The range of possible results is broad, so the figure is imprecise.

What these lines never say