What is the MMR vaccine?

MMR is a 3-in-1 vaccine that protects against measles, mumps and rubella (German measles). The NHS and most medical authorities believe that it offers your child the safest and most effective protection against the three diseases. However, some doctors, including BabyJabs’ Dr Richard Halvorsen, are concerned that the vaccine may cause major problems in some children.

When was the MMR vaccine introduced?

The vaccine was introduced into the UK in 1988 without adequate safety testing.¹ Not one of the safety trials on the MMR ‘actively’ followed up the vaccinated children for more than six weeks, and most no longer than three weeks.² The trials would not have been able to detect either rare, or long-term, side effects of the vaccine, such as autism and bowel disease.

The MMR replaced the single measles vaccine that had been used for the previous 20 years. Initially children received only one MMR vaccine – at 13-15 months – but a second dose was added in 1996, because the vaccine was found to be less effective than at first hoped.

There are currently two MMR vaccines licensed for use in the UK: Priorix, made by GlaxoSmithKline, and M-M-R-VaxPro, made by Sanofi Pasteur MSD. The vaccines contain different strains of measles and mumps vaccine, but are very similar in terms of safety and effectiveness.

The vaccines contain three live viruses that have been ‘attenuated’ or made safe. Both vaccines contain the equivalent of the three single vaccines given in one injection.

When is the MMR vaccine given?

It is given as part of the NHS schedule at 13 months, and again at 3 to 4 years of age. The second vaccine is not strictly a ‘booster’, in that it is not necessary if all three parts of the first MMR worked; it is, rather, a second chance for the child to be protected, in case one or more parts failed to work first time round.

How well does the vaccine work?

Only one dose of the vaccine is needed to provide protection, but, like all vaccines, it does not work in everyone. The effectiveness of the vaccine varies between its different components: both the measles and rubella parts work well, protecting at least 9 out of every 10 children immunised, whereas the mumps part works less well, protecting two children out of very three vaccinated. After two doses of the vaccine, nearly all children are protected against measles and rubella, and around eight out of every nine children against mumps. It is not known how long the effect lasts, but most children will remain protected well into adulthood.

Is the MMR more effective than the single vaccines?

No. The MMR is no more effective than the single measles, mumps and rubella vaccines. In fact, the single mumps vaccine may be more effective than the mumps component of the MMR: the percentage of children protected against mumps by one dose of the single mumps vaccine is estimated to be 75%-97%, whereas the effectiveness of the mumps component of the MMR vaccine, calculated from an outbreak of mumps in North East London in 1998/9, is that a single dose is only 64% effective.^{3 4}

How safe is the MMR vaccine? Can the vaccine cause autism?

Fears were aroused that the vaccine might be causing autism and bowel disease in some children following the publication of research in 1998.⁵ At the sane time Dr Andrew Wakefield, one of the paper’s authors, recommended giving the three single vaccines separately, instead of the triple MMR. This suggestion has been strongly rejected by the government and medical establishment. Though most parents continued to give their children the MMR vaccine, the single vaccines have remained in demand, with more than 1 in 20 children being given at least one of the single vaccines.⁶

At around the time of the introduction of the MMR, the number of cases of autism being diagnosed started to increase dramatically, and some feared that the MMR might have triggered this rise. Experts debated whether the rise was even real, or whether it was due to increased recognition and diagnosis of autism. Most experts now agree that the large rise has been caused partly by increased diagnosis, but also by a real increase in the number of children with autism. Research, including large population studies, has since shown that the MMR is not causing the large majority of autism, but has been unable to exclude the possibility that it is causing autism in a small number of susceptible children.^{7 8 9 10} This means that the vaccine could be causing autism in up to 10% of autistic children in the UK – between 300 and 400 children a year.

The vaccine strain measles virus has been found in the guts - and brains – of some autistic children; this research supports many parents’ beliefs that the MMR vaccine has caused autism in their children.^{11 12}

Are there any other side effects?

There have been concerns about the safety of the MMR vaccine ever since its introduction. Two of the initial three MMR vaccines used in the UK were withdrawn in 1992 because they were causing some children to be hospitalised with a form of meningitis.

Side effects are common after the MMR: 1 in 6 children will develop a fever, usually around 7-10 days after immunisation; in 1 in 20 the fever will be high (over 39.5°C).¹³ Diarrhoea and rash are common side effects. More convulsions (fits) occur after the MMR vaccine than any other vaccine routinely used in the UK. 1 in 750 children have a fit after being given the MMR and these children have an increased risk of going on to suffer further febrile convulsions (fits caused by a fever). Children who have had a febrile convulsion before receiving the MMR have a 1 in 50 chance of a further convulsion after having the vaccine.¹⁴

The vaccine causes a first attack of Idiopathic Thrombocytopaenia Purpura (ITP) in 1 in 25,000 children receiving the vaccine. ITP is a rare immune related bleeding disorder, from which most children make a full recovery.¹⁵

Receiving the MMR vaccine may increase the risk of asthma and eczema. The vaccine can cause encephalitis, an infection of the brain that can be fatal, but this is probably extremely rare.

Are side effects less likely after the single vaccines?

Most of the side effects of the MMR also occur with the single vaccines. However, two side effects are over three times more likely to occur after the MMR than after the single vaccines: these are febrile convulsions (fits as a result of a fever) and Idiopathic Thrombocytopaenia Purpura (ITP), a rare bleeding disorder that can be serious.^{16 17}

It is very likely that the MMR causes autism and bowel disease in some children. It is probable that the single measles vaccine can also do this, but, if so, much more rarely than the MMR. There are several reasons for this assumption:

1. Parents of over a thousand children believe that their child has been made autistic as a result of receiving the MMR vaccine. This is frequently dismissed as anecdotal evidence, but should not be ignored. Whilst it is likely that some of these parents are mistaken, it seems improbable that all are mistaken; parents know their children better than anyone else and are usually correct in their assertions. Very few parents have implicated the single measles vaccine in their child’s autism or bowel disease.
2. The large majority of children purportedly made autistic as a result of vaccination, and examined in clinical studies, have received the MMR vaccine, but not any other measles-containing vaccine.
3. The MMR vaccine contains three live viruses. It is the first vaccine ever used on a large scale to contain more than one live virus. This could result in unpredictable effects.

Does BabyJabs offer the MMR vaccine?

We do not offer the MMR vaccine at BabyJabs We are concerned that the safety of the vaccine has not been adequately demonstrated, and believe that the single vaccines are suitable alternatives that are equally – possibly more – effective and are probably safer.


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¹ Jefferson T, Price D, et al. Unintended events following immunization with the MMR: a systematic review. Vaccine 2003; 21: 3954-3960.

² Wakefield AJ, Montgomery SM. Measles, mumps, rubella vaccine: through a glass darkly. Adverse Drug Reactions and Toxicological Reviews 2000; 19: 265-83.

³ Hilleman MR et al. Live attenuated mumps-virus vaccine. 4. Protective Efficacy as Measured in a Field Evaluation. New England Journal of Medicine 1967; 252-7.

⁴ Lewis JE et al. Epidemic of mumps in a partially immune population. Canadian Medical Association Journal 1979; 121: 751-4.

⁵ Wakefield AJ et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet 1998; 351:637-41.

⁶ Pearce A, Law C, Elliman D, Cole TJ, Bedford H, the Millennium Cohort Study Child Health Group. Factors associated with uptake of measles, mumps and rubella vaccine (MMR) and use of single antigen vaccines in a contemporary UK cohort: prospective cohort study. BMJ 2008; 336: 754-757.

⁷ Madsen KM et al. A population-based study of measles, mumps and rubella vaccination and autism. The New England Journal of Medicine 2002; 347: 1477-1482.

⁸ Kaye JA et al. Mumps, measles, and rubella vaccine and the incidence of autism recorded by general practitioners: a time trend analysis. British Medical Journal 2001; 322: 460-463.

⁹ Davis RL et al. Measles-Mumps-Rubella and Other Measles-Containing Vaccines do not increase the risk for Inflammatory Bowel Disease. A Case-control Study from the Vaccine Safety Datalink Project. Archives of Pediatric and Adolescent Medicine 2001; 155: 354-359.

¹⁰ Smeeth L. Cook C. Fombonne E. Heavey L. Rodrigues LC. Smith PG. Hall AJ. MMR vaccination and pervasive developmental disorders: a case-control study. Lancet 2004; 364(9438): 963-9.

¹¹ Uhlmann V, Martin CM et al. Potential viral pathogenic mechanism for a new variant inflammatory bowel disease. Molecular Pathology 2002; 55: 84-90.

¹² Bradstreet JJ et al. Detection of Measles Virus Genome RNA in Cerebrospinal Fluid of Children with Regressive Autism: a Report of Three Cases. Journal of American Physicians and Surgeons 2004; 9: 38-45.

¹³ LeBaron CW, Bi D, Sullivan BJ, Beck C, Gargiullo P. Evaluation of Potentially Common Adverse Events Associated With the First and Second Doses of Measles-Mumps-Rubella Vaccine. Pediatrics 2006; 118 (4): 1422-1430.

¹⁴ Vestergaard M et al. MMR Vaccination and Febrile Seizures. Evaluation of Susceptible Subgroups and Long-term Prognosis. Journal of the American Medical Association 2004; 292: 351-357.

¹⁵ Jonville-Bera AP et al. Thrombocytopenic purpura after measles, mumps and rubella vaccination: a retrospective survey by the French regional pharmacovigilance centres and pasteur-merieux serums et vaccines. Pediatric Infectious Disease Journal 1996; 15: 44-8.

¹⁶ Allerdist H. Neurological complications following measles vaccination. Developments in Biological Standardization 1979; 43: 259-64.

¹⁷ Miller C et al. Surveillance of symptoms following MMR vaccine in children. Practitioner 1989; 233: 69-74.