Do
Vaccines Cause Allergic or Autoimmune Diseases?
Paul A. Offit, MD*
and Charles J. Hackett, PhD
Division of
Infectious Diseases, Childrens Hospital of Philadelphia, University of
Pennsylvania School of Medicine, and the Wistar Institute of Anatomy and
Biology, Philadelphia, Pennsylvania
Division of
Allergy, Immunology, and Transplantation, National Institutes of Allergy and
Infectious Diseases, National Institutes of Health, Bethesda, Maryland
Anecdotal case
reports and uncontrolled observational studies in the medical literature claim
that vaccines cause chronic diseases such as asthma, multiple sclerosis, chronic
arthritis, and diabetes. Several biological mechanisms have been proposed to
explain how vaccines might cause allergic or autoimmune diseases. For example,
allergic diseases might be caused by prevention of early childhood infections
(the "hygiene hypothesis"), causing a prolongation of immunoglobulin E-promoting
T-helper cell type 2-type responses. However, vaccines do not prevent most
common childhood infections, and large well-controlled epidemiologic studies do
not support the hypothesis that vaccines cause allergies. Autoimmune diseases
might occur after immunization because proteins on microbial pathogens are
similar to human proteins ("molecular mimicry") and could induce immune
responses that damage human cells. However, wild-type viruses and bacteria are
much better adapted to growth in humans than vaccines and much more likely to
stimulate potentially damaging self-reactive lymphocytes. Consistent with
critical differences between natural infection and immunization, well-controlled
epidemiologic studies do not support the hypothesis that vaccines cause
autoimmunity.
Flaws in proposed
biological mechanisms that explain how vaccines might cause chronic diseases are
consistent with the findings of many well-controlled large epidemiologic studies
that fail to show a causal relationship.
Abbreviations: IgE,
immunoglobulin E Th2, T-helper cell type 2 Th1, T-helper cell type 1 HMO,
health maintenance organization Hib, Haemophilus influenzae type b MBP,
myelin basic protein HBsAg, hepatitis B surface antigen OspA, outer surface
protein A LFA-1, lymphocyte function-associated antigen-1
Received for
publication Jun 14, 2002; accepted Sep 10, 2002.
Pediatrics Online,
20 Mar 2003
Vaccine safety:
causal or coincidental associations
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-- Albert Einstein, letter to a friend, 1901
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-- Thomas Jefferson, letter to William C. Jarvis, September 28, 1820
"What's the point of vaccination if it doesn't protect you from the unvaccinated?"
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