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Date:  Aug. 25, 2011






WASHINGTON — An analysis of more than 1,000 research articles concluded that few health problems are caused by or clearly associated with vaccines.  A committee of experts convened by the Institute of Medicine to review the scientific literature on possible adverse effects of vaccines found convincing evidence of 14 health outcomes -- including seizures, inflammation of the brain, and fainting -- that can be caused by certain vaccines, although these outcomes occur rarely.  It also found indicative though less clear data on associations between specific vaccines and four other effects, such as allergic reactions and temporary joint pain.  In addition, the evidence shows there are no links between immunization and some serious conditions that have raised concerns, including Type 1 diabetes and autism.  The data were inadequate to reach conclusions about other suggested adverse effects.


The review will help the U.S. Department of Health and Human Services (HHS) administer the Vaccine Injury Compensation Program (VICP).  VICP is committed to using science-based evidence to inform its decisions about vaccine-related adverse effects, and HHS turned to IOM to provide a comprehensive review of study results on eight vaccines covered by the program.   The report's findings will be useful to all stakeholders involved in vaccine compensation decisions, including VICP staff, people filing claims, special masters that rule on vaccine cases, and others.   


Convincing evidence shows that the measles-mumps-rubella (MMR) vaccine can lead to fever-triggered seizures in some individuals, although these effects are almost always without long-term consequences, the report says.  The MMR vaccine also can produce a rare form of brain inflammation in some people with severe immune system deficiencies.  In a minority of patients, the varicella vaccine against chickenpox can induce brain swelling, pneumonia, hepatitis, meningitis, shingles, and chickenpox in immunocompromised patients as well as some who apparently have competent immune function, the committee found.  The majority of these problems have occurred in individuals with immunodeficiencies, which increase individuals' susceptibility to the live viruses used in MMR and varicella.  Six vaccines -- MMR, varicella, influenza, hepatitis B, meningococcal, and the tetanus-containing vaccines -- can trigger anaphylaxis, an allergic reaction that appears shortly after injection.  And, in general, the injection of vaccines can trigger fainting and inflammation of the shoulder, the committee noted.  


The evidence suggests that certain vaccines can lead to four other adverse effects, although the data on these links are not as convincing, the report says.  The MMR vaccine appears to trigger short-term joint pain in some women and children.  Some people can experience anaphylaxis after receiving the HPV vaccine.  And certain influenza vaccines used abroad have resulted in a mild, temporary oculo-respiratory syndrome characterized by conjunctivitis, facial swelling, and mild respiratory symptoms.


The committee's review also concluded that certain vaccines are not linked to four specific conditions.  The MMR vaccine and diphtheria-tetanus-acellular pertussis (DTaP) do not cause Type 1 diabetes, and the MMR vaccine does not cause autism, according to the results of several studies.  The evidence shows that the flu shot does not cause Bell's palsy or exacerbate asthma.  Suggestions that vaccines can lead to these serious health problems have contributed to parental concerns about immunization for their children. 


Establishing a cause-and-effect relationship between an agent and a health outcome requires solid evidence.  The committee's conclusions are based on the strengths and weaknesses of several types of evidence, including biological, clinical, and epidemiological research.  In many cases of suggested vaccine-related adverse outcomes, there is too little evidence, or the available evidence offers conflicting results or is otherwise inadequate to draw conclusions.


"With the start of the new school year, it's time to ensure that children are up to date on their immunizations, making this report's findings about the safety of these eight vaccines particularly timely," said committee chair Ellen Wright Clayton, professor of pediatrics and law, and director, Center for Biomedical Ethics and Society, Vanderbilt University, Nashville, Tenn.  "The findings should be reassuring to parents that few health problems are clearly connected to immunizations, and these effects occur relatively rarely.  And repeated study has made clear that some health problems are not caused by vaccines."


In accordance with its charge, the committee focused solely on findings about potential risks of immunizations.  It did not examine information that would have allowed it to draw conclusions about the ratio of benefits to risks.  However, the committee members noted that deaths and disability due to infectious diseases have been dramatically reduced over the last century since the majority of vaccines were developed and brought into widespread use.


The study was sponsored by the U.S. Department of Health and Human Services.  Established in 1970 under the charter of the National Academy of Sciences, the Institute of Medicine provides independent, objective, evidence-based advice to policymakers, health professionals, the private sector, and the public.  The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.  For more information, visit or  A committee roster follows.




Christine Stencel, Media Relations Officer

Luwam Yeibio, Media Relations Assistant

Office of News and Public Information

202-334-2138; e-mail


Additional resources:

Full Report

Project Website  

Report in Brief

Pre-publication copies of Adverse Effects of Vaccines: Evidence and Causality are available from the National Academies Press; tel. 202-334-3313 or 1-800-624-6242 or on the Internet at  Additional information is at  Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).

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Board on Population Health and Public Health Practice


Committee to Review Adverse Effects of Vaccines

Ellen Wright Clayton, J.D., M.D. (chair)
Craig-Weaver Professor of Pediatrics; 
Center for Biomedical Ethics and Society; and 
Professor of Law
Vanderbilt University
Nashville, Tenn.


Inmaculada B. Aban, M.S., Ph.D.
Associate Professor
Department of Biostatistics
University of Alabama

Douglas J. Barrett, M.D.
Departments of Pediatrics, Molecular Genetics and Microbiology, Pathology, Immunology, and Laboratory Medicine
College of Medicine
University of Florida


Martina Bebin, M.D., M.P.A.
Associate Professor of Neurology and Pediatrics
University of Alabama


Kirsten Bibbins-Domingo, Ph.D., M.D., M.A.S.
Associate Professor and Attending Physician
University of California
San Francisco


Martha Constantine-Paton, Ph.D.
McGovern Institute for Brain Research, and
Departments of Biology and Brain and Cognitive Sciences
Massachusetts Institute of Technology


Deborah J. del Junco, Ph.D.
Senior Epidemiologist and Associate Professor of Biostatistics, Epidemiology, and Research Design
Health Science Center
University of Texas


Betty A. Diamond, M.D.
Center for Autoimmune and Musculoskeletal Disease
Feinstein Institute for Medical Research
North Shore-LIJ Health System
Manhasset, N.Y.


S. Claiborne Johnston, M.D., Ph.D.

Associate Vice Chancellor of Research;  

Director of Clinical and Translational Science;

Institute Professor of Neurology and Epidemiology; and 


Neurovascular Disease and Stroke Center

University of California

San Francisco


Anthony L. Komaroff, M.D.
Steven P. Simcox, Patrick A. Clifford, and James H. Higby Professor of Medicine, and
Senior Physician
Brigham and Women’s Hospital
Harvard Medical School

B. Paige Lawrence, Ph.D.
Associate Professor
Departments of Environmental Medicine and Microbiology and Immunology
School of Medicine and Dentistry
University of Rochester
Rochester, N.Y.


M. Louise Markert, M.D., Ph.D.
Associate Professor of Pediatrics and Immunology
Division of Pediatric Allergy and Immunology
Department of Pediatrics
Duke University Medical Center
Durham, N.C.


Marc C. Patterson, M.D.
Division of Child and Adolescent Neurology;  
Professor of Neurology, Pediatrics, and Medical Genetics; and
Child Neurology Training Program
Mayo Clinic
Rochester, Minn.


Hugh A. Sampson, M.D.
Professor of Pediatrics and Immunology; 
Dean for Translational Biomedical Sciences; and
Jaffe Food Allergy Institute
Mount Sinai School of Medicine
New York City


Pauline A. Thomas, M.D.
Associate Professor
Department of Preventive Medicine and Community Health
New Jersey Medical School, and
Associate Professor
School of Public Health
University of Medicine and Dentistry of New Jersey


Leslie P. Weiner, M.D.
Richard Angus Grant, Sr. Chair in Neurology, and
Professor of Neurology and Molecular Microbiology and Immunology
Keck School of Medicine
University of Southern California
Los Angeles




Kathleen Stratton, Ph.D.

Study Director