3c.2. There is some risk of anaphylaxis. This risk is low; from the time that VAERS was instituted in 1990 till the publication of Update: Vaccine Side Effects, Adverse Reactions, Contraindications, and Precautions by ACIP in 1996, >70 million doses of MMR vaccine had been distributed in the US, and only 33 cases of anaphylactic reactions had been reported to VAERS. It has been traditionally believed that this risk is mainly for people allergic to eggs or neomycin. However, recent studies indicate that anaphylactic reactions are not associated with egg allergies, but with some other component of the vaccine. There have been some case reports, in the US and Japan, of anaphylactic reactions to the MMR vaccine in people with an anaphylactic sensitivity to gelatin.
Description
This article is from the Childhood Vaccinations FAQ, by Lynn Gazis-Sax lynng@alsirat.com with numerous contributions by others.
3c.2. There is some risk of anaphylaxis. This risk is low; from the time that VAERS was instituted in 1990 till the publication of Update: Vaccine Side Effects, Adverse Reactions, Contraindications, and Precautions by ACIP in 1996, >70 million doses of MMR vaccine had been distributed in the US, and only 33 cases of anaphylactic reactions had been reported to VAERS. It has been traditionally believed that this risk is mainly for people allergic to eggs or neomycin. However, recent studies indicate that anaphylactic reactions are not associated with egg allergies, but with some other component of the vaccine. There have been some case reports, in the US and Japan, of anaphylactic reactions to the MMR vaccine in people with an anaphylactic sensitivity to gelatin.
In rare instances, MMR vaccine can cause clinically apparent
thrombocytopenia within 2 months after vaccination. Passive
surveillance systems report an incidence of 1 case per 100,000 doses
in Canada and France, and 1 per million in the US. Prospective
studies have reported a range from 1 in 30,000 in Finland and Great
Britain to 1 in 40,000 in the US, with a clustering of cases about 2-3
weeks after vaccination.
An article in the Feb 28, 1998 Lancet (based on 12 cases) about a
possible association between inflammatory bowel disease, autism, and
MMR vaccine (Wakefield et al) raised concerns that the vaccine might
increase the risk of autism. Wakefield and his colleagues did not
claim to have actually shown that the vaccine caused autism, but
rather called for further investigation of the question. An
accompanying editorial in the same issue of Lancet expressed concerns
about the validity of the study.
The article, and the public concern it raised, led to several further
investigations of whether such an association existed. A research
letter in the May 2, 1998 issue of Lancet reported on a 14-year
prospective study, in Finland, of children who had experienced
gastrointestinal symptoms after receiving the MMR vaccine. 31 children
(out of 3 million vaccine doses) reported gastrointestinal symptoms;
all recovered, and none developed autism. A Working Party on MMR
Vaccine of the United Kingdom's Committee on Safety of Medicines
(1999) examined hundreds of reports, collected by lawyers, of autism
or Crohn's disease (a gastrointestinal disease) and similar problems,
after the MMR vaccine, and concluded that there was no causal
relationship. A Swedish study (Gillberg and Heijbel 1998) found no
difference in the prevalence of autism in children born before the
introduction of MMR vaccine in Sweden, and children born
after. Wakefield and colleagues did laboratory assays in patients with
inflammatory bowel disease (the mechanism which they had proposed for
autism following the MMR vaccine), and found them negative for measles
virus (Chadwick 1998, Duclos 1998, cited by the CDC at
http://www.cdc.gov/nip/vacsafe/vaccinesafety/sideeffects/autism.htm).
Finally, a study in the June 12, 1999 issue of Lancet examined
children born with autism since 1979 in eight North Thames health
districts, to look for changes in incidence or age at diagnosis since
the introduction of MMR vaccination in the UK in
1988. The study found a steady increase in cases of autism, with no
sudden change in the trend after the introduction of the
MMR vaccine. Parents most frequently reported first noticing symptoms
of autism at around the age of 18 months, after the MMR vaccine would
have been received, but there was no difference in age at diagnosis
between those vaccinated before and after 18 months and those never
vaccinated. Developmental regression (which occurred in about a third
of the cases of autism) was not clustered in the months after
vaccination.
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