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Vaccine ingredients

Article source:Station editor Update time:2018-07-24 10:12:58   Browsing times:second

Active ingredients

These are the parts of the vaccine made from viruses or bacteria (also called ‘antigens’). They challenge the immune system so that it makes antibodies to fight the disease. Vaccines contain tiny quantities of active ingredients – just a few micrograms (millionths of a gram) per vaccine. To give some idea of how small these quantities are, one paracetamol tablet contains 500 milligrams of the drug. This is several thousand times more than the quantity of the active ingredient you would find in most vaccines. Hundreds of thousands of individual vaccines could be made from a single teaspoon of active ingredient.
Some vaccines contain whole bacteria or viruses. In these cases the bacteria or viruses will either be severely weakened (attenuated) so that they cannot cause disease in healthy people, or killed altogether (inactivated). Many vaccines contain only parts of viruses or bacteria, usually proteins or sugars from the surface. These stimulate the immune system but cannot cause disease.
Compared to the number of viruses and bacteria in the environment that our bodies have to deal with every day, the amount of active ingredient in a vaccine is very small indeed. Most bacterial vaccines contain just a few proteins or sugars from the relevant bacterium. By contrast it is estimated that 100 trillion bacteria live on the skin of the average human being, each of them containing many thousands of proteins which constantly challenge our immune systems.
A few vaccines in the UK schedule are made using recombinant DNA technology. Only one vaccine used in the UK contains genetically modified organisms (GMOs).
More detail about active ingredients can be found on each of the pages about individual vaccines.
A few products used in vaccine manufacture are a risk to some people, even in trace amounts, because they can cause allergic reactions (for example, egg proteins and antibiotics). These products are always clearly stated on vaccine information leaflets. Other items are present in such tiny quantities that they do not pose a risk.
A complete list of vaccine ingredients can be found on the Patient Information Leaflet (PIL) and Summary of Product Characteristics (SPC) sheet for each vaccine. See the list of PILs and SPCs on our links page.
Added ingredients
These are products such as aluminium salts that help to improve the immune response to vaccines, or products that act as preservatives and stabilisers (for example, gelatine or human serum albumin). These are listed on vaccine information leaflets as ‘excipients’ (inactive ingredients). Like vaccines, most of the medicines we use also contain excipients. Most vaccines do not now contain the preservative thiomersal (also called thimerosal).
Aluminium (an adjuvant)
Many vaccines contain aluminium salts such as aluminium hydroxide, aluminium phosphate or potassium aluminium sulphate. They act as adjuvants, strengthening and lengthening the immune response to the vaccine. Aluminium salts appear to slow down the release of the active ingredient from the vaccine once it is injected, and stimulate the immune system to respond to the vaccine. They also absorb protein well, and stop the proteins in the vaccine sticking to the walls of a container during storage.
Aluminium is the most common metal in the earth’s crust and we are exposed to it all the time. It reacts with other elements to form aluminium salts, and small amounts of these are found naturally in almost all foods and drinking water, as well as in breast milk and in formula milk for babies. Aluminium salts are used as food additives (for example in bread and cakes) and in drugs such as antacids, and aluminium is widely used in food packaging.
Aluminium is not used by the body. Any aluminium absorbed from food or other sources is gradually eliminated through the kidneys. Babies are born with aluminium already present in their bodies, probably from the mother’s blood. Over time, small amounts of the aluminium from food, drink and other sources do accumulate in the body, but this is not believed to pose a significant risk to health (see for example this UK research from 2004 ). The view of most experts is that there is currently no convincing evidence that exposure to everyday levels of aluminium in any form increases the risks of Alzheimer’s disease, genetic damage or cancer.
The amount of aluminium present in vaccines is small - less than 2 milligrams of the salts, and less than a milligram of actual aluminium. In the UK, the highest dose of aluminium that babies receive in one go from vaccines is just under 1.5 milligrams (from the 6-in-1, PCV and MenB vaccines at 8 weeks and 16 weeks). A study from 2011  modelled the impact of aluminium from diet and vaccines in infants, and concluded that the total amount of aluminium absorbed from both sources was likely to be less than the weekly safe intake level. A study from 2002  drew similar conclusions.
Rarely, aluminium adjuvants may cause small itchy lumps (granulomas) to form at the injection site. A 2014 Swedish study  found that this happened in a small number of children (fewer than 1 in 100) after vaccination with the 5-in-1 vaccine (Infanrix) and pneumococcal vaccine (Prevenar). Granulomas are not dangerous but can be irritating and last for months or even years. The study found that children with granulomas often developed an aluminium contact allergy. However, most children recovered from their symptoms.
Aluminium salts are found in these vaccines used routinely in the UK. The exact amounts of aluminium per dose are listed for each vaccine:
6-in-1 vaccine: Infanrix Hexa (0.82 milligrams)
PCV (pneumococcal conjugate vaccine): Prevenar 13 (0.125 milligrams)
MenB vaccine: Bexsero (0.5 milligrams)
Pre-school Booster vaccines: Repevax (0.33 milligrams), Infanrix IPV (0.5 milligrams) and Boostrix-IPV (0.5 milligrams)
HPV vaccine: Gardasil (0.225 milligrams)
Teenage Booster vaccine: Revaxis (0.35 milligrams)
HepB vaccine: HBVaxPro (0.25 to 0.5 milligrams, depending on which version of HBVaxPro is given)
MF59 (squalene oil), an adjuvant
MF59 is used in only one vaccine licensed in the UK: Fluad, a flu vaccine introduced in the 2018-19 flu season for adults aged 65 and older (see the page on the Inactivated Flu Vaccine). Fluad is not a new vaccine; it was first licensed in 1997 and millions of doses have been given worldwide. MF59 is added to the vaccine to make it more effective. It is an adjuvant which helps to strengthen and lengthen the immune response to the vaccine.
The main ingredient in MF59 is squalene oil, a naturally-occurring oil found in humans, plants and animals. The squalene oil in MF59 comes from fish oil and is highly purified before it is used. Fluad contains less than 10mg of squalene (1mg is one thousandth of a gram).
MF59 also contains very small amounts of these ingredients (around 1mg or less):
polysorbate 80, sorbitan trioleate and sodium citrate. These are all emulsifiers which stop the squalene oil separating out from the water in the vaccine. Polysorbate 80 and sodium citrate are commonly used in food and drink. Sorbitan trioleate is a compound made from oleic acid (a natural fatty acid) and sorbitol, also found naturally in fruits and other foods.
citric acid, used extensively in foods and drinks.
Thiomersal, also called thimerosal in the US (a preservative)
Thiomersal is a mercury-based preservative used in tiny quantities in some vaccines to prevent the growth of bacteria and fungi which can contaminate from the environment when the vaccine is opened.
Most single-dose vaccines do not contain thiomersal because they are used only once and so there is very little risk of contamination. However, some vaccines are produced in multi-dose vials. There are two reasons for this: they are cheaper, and they are easier to produce quickly in large quantities in the event of an epidemic. Tiny quantities of thiomersal are often used in multi-dose vaccines to stop them becoming contaminated once they are opened.
Thiomersal was removed from UK vaccines between 2003 and 2005, and is no longer found in any of the childhood or adult vaccines routinely used in the UK. Before 2005, thiomersal was present in diphtheria- and tetanus-containing vaccines, as well as hepatitis B vaccine and some flu vaccines. It was not used in the MMR vaccine, the Hib vaccine, the MenC vaccine, the oral polio vaccine or the BCG vaccine. Since 2005, thiomersal has only been present in non-routine vaccines such as hepatitis B, and occasionally in some of the annual inactivated flu vaccines. Thiomersal was present in the Swine Flu (H1N1) vaccine Pandemrix, used in the 2009-10 and 2010-11 flu seasons in the UK. However, it is not present in any of the annual flu vaccines currently in use in the UK.
In the US, UK and Europe, thiomersal was removed from vaccines as a precaution. This was in line with the global goal of reducing environmental exposure to mercury from all sources. However, there was no evidence that thiomersal in vaccines caused harm. Thiomersal contains a compound called ethyl mercury, but concern about mercury in the environment has centred on a different compound called methyl mercury, which accumulates in the food chain and in the human body. More detailed information can be found on the US National Institute of Allergy and Infectious Disease  website. A study from 2008  showed that the ethyl mercury in thiomersal does not appear to accumulate in the bodies of even very small babies. It is cleared from the blood in 30 days, and the evidence suggests that it is passed out in the baby’s stool (poo).
The World Health Organization (WHO) and the European Medicines Agency (EMA, previously EMEA) have both stated that there is no evidence of risk from thiomersal in vaccines. Read the WHO statement  and the EMA statement . There is also detailed information about the safety of thiomersal on the US Food and Drug Administration's pages .
A 2014 Australian study of over a million children  found no evidence of a link between thiomersal in vaccines and autism development.
Gelatine (a stabiliser)
Gelatine derived from pigs is used in some live vaccines as a stabiliser to protect live viruses against the effects of temperature. Gelatine in vaccines is highly purified and hydrolysed (broken down by water), so it is different from the natural gelatine used in foods. For example, very sensitive scientific tests have shown that no DNA from pigs can be detected in the nasal flu vaccine (Fluenz). These tests show that the gelatine is broken down so much that the original source cannot be identified.
There have been a tiny number of cases of allergic reaction to vaccines containing gelatine (about one case for every 2 million doses of vaccine). People with a known allergy to gelatine should seek expert advice before receiving vaccines containing gelatine.
Members of Muslim or Jewish religious communities may be concerned about using vaccines that contain gelatine from pigs (porcine gelatine). According to Jewish laws, there is no problem with gelatine or any other animal substance if it is used in a product that does not go into the mouth. Some Muslim leaders have also ruled that the use of gelatine in vaccines does not break religious dietary laws, because it is highly purified and it is also injected rather than ingested (eaten). This issue was addressed by a Public Health England statement  issued in October 2013.
Gelatine is found in these vaccines used in the UK:
one of the MMR vaccines (MMRVaxPro). (Priorix, the other MMR vaccine used in the UK, does not contain gelatine.)
the Nasal Flu vaccine (Fluenz). However, very sensitive scientific tests have shown that no DNA from pigs can be detected in Fluenz. These tests show that the gelatine is broken down so much that the original source cannot be identified.
the shingles vaccine (Zostavax)
one of the chickenpox vaccines (Varivax). (Varilrix, the other chickenpox vaccine used in the UK, does not contain gelatine.)
More information can be found in the NHS leaflet 'Vaccines and porcine gelatine' .
Human Serum Albumin (a stabiliser)
Human serum albumin is the most common protein found in human blood. It is currently used in very small quantities as a stabiliser in one of the chickenpox vaccines used in the UK (Varilrix). It comes from blood donors who are screened, and the manufacturing process takes away any risk of passing on viruses from the serum. No viral diseases have ever been linked to the use of human serum albumin.
Recombinant human serum albumin (a stabiliser)
One of the MMR vaccines used in the UK, MMRVaxPro, contains a very small amount of recombinant human serum albumin (0.3 mg per dose). Recombinant albumin does not contain any human or animal products. The albumin is produced by cells (such as yeast cells) that have had the gene for human albumin inserted into them. The cells are then able to generate large quantities of human serum albumin without any need to extract it from human blood.
Sorbitol and other stabilisers
Sorbitol is produced naturally in the human body and also found in fruit and berries. It is commonly used as a sweetener in foods and drinks. In vaccines it is used in small quantities as a stabiliser. There may be up to 15 milligrams of sorbitol in the MMR vaccines used in the UK (MMR VaxPro and Priorix). Sorbitol may also be present in one of the chickenpox vaccines (Varilrix). Sorbitol is usually harmless, but people with an allergy to sorbitol, or with rare inherited problems of fructose intolerance, should not receive vaccines containing sorbitol.
Other products used in very small quantities as stabilisers in vaccines include:
Sugar (sucrose)
Lactose (milk sugar)
Mannitol, similar to sorbitol – see above
Glycerol, a common non-toxic substance often used as a food additive
Medium 199, a solution which contains amino acids (the building blocks of proteins), mineral salts and vitamins
Monosodium glutamate, a salt made from the amino acid glutamine
Urea, a harmless organic compound found in the human body
Polysorbate 80 is a common food additive used in several vaccines as an emulsifier (to hold other ingredients together). Compared to its use in foods, there is very little polysorbate 80 in vaccines.