A fever of 39.4oC or more occurs in 5–15 percent of children and generally lasts one to two days. Rash occurs in approximately 5 percent of children 6 to 12 days after immunisation. A placebo-controlled study has shown that fever and/or rash in most cases are unrelated to immunisation, and only rash in 1.6 percent and high fever in 1.4 percent of cases could be attributed to MMR; these fevers were most likely nine or 10 days after immunisation and the rash occurred in the second week.25
The mumps vaccine may produce parotid and/or submaxillary swelling in about 1 percent of vaccinees, most often 10 to 14 days after immunisation. The rubella vaccine can cause a mild rash, fever and lymphadenopathy between two and four weeks after immunisation. There were no persisting sequelae associated with the administration of three million doses of MMR to 1.5 million children in Finland.25 , 26
Febrile seizures occur in approximately 1 in 3000 children, 6 to 12 days after immunisation. Parents/guardians should be advised that along with other cooling measures, they can give the child an age-appropriate dose of paracetamol if there is fever greater than 39oC (see section 2.3.13 for more detail on the use of paracetamol and other antipyretics). Children with a history of seizures should be given MMR, but the parents/guardians should be warned that there may be a febrile response and encouraged to use cooling measures and/or antipyretics if fever develops. After re immunisation, reactions are expected to be clinically similar but much less frequent, since most vaccine recipients are already immune. No unusual reactions have been associated with MMR re-immunisation.25
MMR vaccine viruses have been regarded as being non-transmissible from vaccinees. There are two poorly documented case reports of transmission: one of rubella and one of a mumps vaccine strain from a vaccine that is no longer in production.27 Following immunisation with both measles and rubella vaccines, live virus has been isolated rarely from pharyngeal secretions.28, 29 There have been no conﬁrmed cases of disease transmission from MMR vaccine viruses.
MMR vaccine is the only childhood vaccine with an elevated risk of immune thrombocytopenic purpura (ITP), which occurs in approximately 1 in 30,000 doses, 15 to 35 days after immunisation. A review of data from 1.8 million children in the US found 197 cases of ITP, with an incidence risk ratio of 5.48 (95% CI: 1.61–18.64).30 If ITP occurs, measles, mumps and rubella serology should be measured, and if the individual is immune to all three infections, a second dose is not required. However, if the individual is susceptible to any of the three infections, a second dose should be administered.31–34
Central nervous system symptoms following measles vaccine are reported to occur in approximately 1 in 1 million children. In most cases this seems to be a chance occurrence not caused by the vaccine. An analysis of claims for encephalitis following measles vaccine in the US found clustering of events at eight to nine days after immunisation.35 This clustering supports, but does not prove, the claim that the vaccine causes encephalitis, albeit rarely and at a lower rate than the wild virus illness. For comparison, the rate of encephalitis following measles disease is approximately 1 in 1000.
MMR containing the Urabe strain of mumps was withdrawn internationally in 1992 following a UK study that found a 1 in 11,000 risk of mumps vaccine meningitis. MMR containing the Urabe strain was used in New Zealand from 1991 until it was withdrawn in 1992. Aseptic meningitis occurs in 1 in 800,000 doses following administration of the Jeryl Lynn strain of mumps vaccine,36, 37 which is used in New Zealand. For comparison, aseptic meningitis occurs in 15 percent of cases of mumps.
Arthritis or arthralgia occurs after both the rubella disease and vaccine, especially in adults. About 15 percent of adult women and fewer than 1 percent of children get joint symptoms about two to four weeks after immunisation. There is no evidence to suggest that rubella vaccine leads to chronic long-term arthritis: two large controlled studies found no evidence,38, 39 while another study did ﬁnd a slight increase in arthritis risk following rubella vaccine, but this was of borderline statistical signiﬁcance.40 A 2012 Institute of Medicine review concluded that the evidence was inadequate to accept or reject a causal relationship between MMR vaccine and chronic arthritis in women.41
Table 11.1 shows the complications associated with contracting measles, mumps and rubella, and from receiving MMR vaccine.
|Otitis media, pneumonia, diarrhoea||1/10–100|
|Encephalitis, probably resulting in brain damage||1/1000|
|Orchitis||1/5 post-pubertal males|
|Congenital rubella: cataracts, deafness, cardiac malformations and brain damage. Some abnormality of the fetus will be detectable in 85 percent of women infected in the ﬁrst eight weeks of pregnancy (see Table 18.1).|
|Vaccine adverse effects|
|Rashes, fever, local reactions, parotid swelling||1/7|
|Transient joint symptoms – children||1/35|
There have been multiple epidemiological studies published from the UK,42 Finland43 and elsewhere44, 45 conﬁrming that there is no link between MMR vaccine and the development of autism in young children. A Japanese case-control study assessed the relationship between autistic spectrum disorder and general vaccinations, including MMR, in a genetically similar population. In this study, MMR vaccination and increasing the number of vaccine injections were not associated with an increased risk of autistic spectrum disorder (see section 3.3.1 for further discussion on this issue).