MMR Vaccine


Key Facts

This vaccine gives protection against measles, mumps, and rubella.

A first dose is given at 12-13 months in the UK schedule. The vaccine is not given earlier than this because studies have shown it does not work well in children under 1 year of age. A booster dose is given at 3 years and 4 months. There is also a catch-up programme for children and teenagers aged 10-16 who missed out on the MMR vaccine as babies.

Before the introduction of the MMR vaccines, measles, mumps, and rubella were extremely common diseases — the majority of people had them at some point. They caused serious disease (including fatal pneumonia and inflammation of the brain with measles, and meningitis with mumps), and led to many deaths. Rubella caused many babies to be born with serious abnormalities.

There are now a large number of studies that show no evidence at all of any link between the MMR vaccine and autism. In the short film below, experts say why they believe there is no link. See the list of studies on this page.


The vaccine contains live, but weakened (attenuated) strains of the measles, mumps and rubella viruses.

The measles and mumps virus strains are grown on a culture which contains chick embryo cells (see more information about the use of animal cell-lines to grow viruses for vaccines). There is not enough egg protein in the MMR vaccine to cause allergic reactions, so children with severe egg allergies can safely receive the MMR. In the short film below, Professor Simon Dobson explains how we know this. Also see more information on egg proteins in vaccines on our Ingredients page.

The rubella virus strain is grown in the laboratory using human cell-lines. See more information on human cell-lines.

There are two MMR vaccines recommended for use in the UK. Both may contain traces of neomycin, an antibiotic used in the production process. See more information on antibiotics in vaccines.

One of the MMR vaccines used in the UK (MMR VaxPro) contains gelatine derived from pigs. The other MMR vaccine used in the UK (Priorix) does not contain gelatine. See more information on gelatine in vaccines.

The vaccine may also contain tiny amounts of products used during the manufacturing process. Click on the links to see more information on our Ingredients page:

The MMR vaccines used in the UK do not contain the preservative thiomersal (mercury).

Side Effects

The three viruses in the MMR act over different time periods. The following side effects are common but not serious:

  • six to ten days after vaccination: a raised temperature, loss of appetite, and measles-like rash. This can happen when the measles part of the vaccine starts to work, and is normal.
  • More rarely children may get mumps-like symptoms (slightly raised temperature and swollen glands) about three weeks after their immunisation as the mumps part of the vaccine starts to work.
  • The rubella element can cause inflammation in joints (arthritis). Though quite common in adult women, in children this is rare, and usually disappears quickly.

More serious side effects are rare:

  • high temperatures, sometimes leading to fits (also called convulsions or febrile seizures)
  • very rarely, a skin rash of small, bruise-like spots up to six weeks after vaccination (immune thrombocytopenic purpura)

You should consult your doctor if these reactions happen after vaccination. This is mainly to check that it is the vaccine causing the symptoms, and not some unrelated disease. Symptoms such as fits can be very worrying for parents, but there is no evidence of long-term effects. Children can normally safely receive vaccines in the future.

As with any vaccine, medicine or food, there is a very small chance of a severe allergic reaction (anaphylaxis). Anaphylaxis is different from less severe allergic reactions because it causes life-threatening breathing and/or circulation problems. It is always serious but can be treated with adrenaline. In the UK between 1997 and 2003 there were a total of 130 reports of anaphylaxis following ALL immunisations, but all of these people survived. Around 117 million doses of vaccines were given in the UK during this period, making the overall rate around 1 in 900,000. Depending on the cause of the reaction, and following expert guidance, the person may be able to have vaccinations in the future.

Reactions listed under ‘possible side effects’ or ‘adverse events’ on vaccine product information sheets may not all be directly linked to the vaccine. See Vaccine side effects and adverse reactions for more information on why this is the case.

See more information on the monitoring of vaccine safety.

MMR and Autism: research references

There are now a large number of studies that show no evidence at all of any link between the MMR vaccine and autism. Autism is a developmental disorder which is usually diagnosed in pre-school children. The original research which suggested a link has now been discredited. The National Autistic Society has issued a statement stating that the weight of evidence points to the fact that ‘there is no statistically significant link between the MMR vaccine and autism’.

Below is a list of studies and their findings. Click on the links to view the abstracts (summaries) of the scientific papers:

Published by Sarah Loving
Medical content reviewed by Professor Andrew Pollard
Please email us if you have comments about the Vaccine Knowledge website. We can’t answer all the individual queries we get, but we will use your suggestions and questions to improve the website. You should consult your doctor or other healthcare provider if you need specific advice on vaccines for you or your child.
Last updated 31 May 2016

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How do we know that the MMR vaccine doesn’t cause autism?

PHE infographic: the impact of vaccination on Measles and other diseases

What to expect from the MMR vaccine - A film from Buckinghamshire County Council