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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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1

Introduction

Protecting health is a major priority of society, families, and individual parents. Over the past 100 years there has been a revolution in the ability to protect health in the developed world, where there are resources to enable this to happen. In 1900, among every 1,000 babies born in the United States, 100 would die before their first birthday, and five before 5 years of age (Guyer et al., 2000). By 2007, fewer than seven were expected to die before their first birthday, and only 0.29 per 1,000 before 5 years of age (HHS, 2010). Diseases severe enough to kill children and adults can also leave survivors disabled in some way, and as mortality has fallen, so has the chance of severe disability from these diseases.

Among the dangers for children and adults that have greatly diminished over the past century are infectious diseases. For bacterial diseases, antibiotics have been developed to treat infections before permanent harm can occur. For many viral and bacterial diseases, vaccines now exist.

In the early 20th century, smallpox (which has 30 percent mortality and a very high rate of disfigurement and other less common sequelae including blindness and encephalopathy) and rabies (virtually 100 percent fatal) could be prevented with immunization (CDC, 2001, 2008). With the fast growing understanding of microbes and immunity from 1920 onward, the development of immunizations became a race to “conquer” infectious disease. Beginning with the combination diphtheria, pertussis, and tetanus immunization during World War II and most recently with immunization to prevent cervical cancer (the human papillomavirus vaccine), immunizations have changed our expectations for child and adult health. Infections are less of a terror, and children are expected to survive to adulthood.

Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Vaccines function by stimulating the immune system and prompting a primary immune response to an infecting pathogen or to molecules derived from a particular pathogen. The immune response elicited by this primary exposure to vaccine pathogen creates immunological memory, which involves the generation of a pool of immune cells that will recognize the pathogen and mount a more robust or secondary response upon subsequent exposure to the virus or bacterium. In successful immunization, the secondary immune response is sufficient to prevent disease in the infected individual, as well as prevent the transmission of the pathogen to others. For communicable diseases, immunizations protect not only the individual who receives the immunization, but also others with whom he or she has contact. High levels of vaccination in a community increase the number of people who are less susceptible or resistant to illness and propagation of the infectious agent. Unvaccinated individuals or those who have not developed immunity to this pathogen are afforded an indirect measure of protection because those with immunity reduce the spread of the pathogen throughout the entire population. The larger the proportion of people with immunity, the greater the protection of those without immunity. This effect is called “herd immunity.” Herd immunity is an important phenomenon as immunization programs rarely achieve 100 percent immunization in a population; and in some cases, previously vaccinated persons may not exhibit effective immunity and disease may result from exposure to the pathogen. For protection, immunization of not only ourselves but also our neighbors is important.

The overwhelming safety and effectiveness of vaccines in current use in preventing serious disease has allowed them to gain their preeminent role in the routine protection of health. Before an immunization is introduced for population-wide use, it is tested for efficacy and safety. However, immunization is not without risks. For example, it is well established that the oral polio vaccine on rare occasion causes paralytic polio and that vaccines sometimes lead to anaphylactic shock. Given the widespread use of vaccines; state mandates requiring vaccination of children for entry into school, college, or day care; and the importance of ensuring that trust in immunization programs is justified, it is essential that safety concerns receive assiduous attention.

Congress passed the National Childhood Vaccine Injury Act (NCVIA, P.L. 99-660) in 1986. The legislation was intended to bolster vaccine research and development through federal coordination of the vaccine efforts in government and by providing relief to vaccine manufacturers who reported at the time that financial burdens from awards in the tort system threatened their financial viability. The legislation was also intended to address concerns about the safety of vaccines by instituting a compensation program financed by an excise tax on covered vaccines, setting up a passive surveillance system for vaccine adverse events, and by providing informa-

Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
×

tion to consumers (CDC, 2010). Key provisions of the 1986 legislation include

  • The establishment of the National Vaccine Program Office, which coordinates immunization-related activities between all Department of Health and Human Services (HHS) agencies including the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration, the National Institutes of Health, and the Health Resources and Services Administration (HRSA).
  • The requirement that all health care providers who administer vaccines provide a vaccine information statement (VIS) to the vaccine recipient, or his or her parent or legal guardian, prior to each dose. Each VIS contains a brief description of the disease as well as the risks and benefits of the vaccine. The CDC develops VISs and distributes them to state and local health departments as well as individual providers.
  • The requirement that health care providers must report certain and are encouraged to report other adverse events (health effects occurring after immunization that may or may not be related to the vaccine) following vaccination to the Vaccine Adverse Event Reporting System.
  • The creation of the National Vaccine Injury Compensation Program (VICP) to compensate those injured by vaccines on a no-fault basis. Importantly, this compensation system has two parts:
    • The Secretary of Health and Human Services has created a Vaccine Injury Table (Table) that “lists and explains injuries/conditions that are presumed to be caused by vaccines. It also lists time periods in which the first symptom of these injuries/ conditions must occur after receiving the vaccine. If the first symptom of these injuries/conditions occurs within the listed time periods, it is presumed that the vaccine was the cause of the injury or condition unless another cause is found” (http://www.hrsa.gov/vaccinecompensation/table.htm) and compensation is awarded.
    • Individuals who assert that they suffered an injury from a vaccine that is not on the Table (“off-Table” or “causation-in-fact”) must pursue their claim before Special Masters, who are appointed by the United States Court of Federal Claims, which hears any appeals. Claimants bear the burden of proving that the vaccine caused their injury, although the burden of proof is lower than that in the tort system.

A key component of the legislation, found in Sections 312 and 313, required the HHS secretary to consult with the Institute of Medicine (IOM)

Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
×

to review the scientific literature on vaccine safety. Two reports were issued (IOM, 1991, 1994). These reports contain a framework for causality assessment of vaccine adverse events.1 The reports addressed the vaccines covered by the VICP up to that point: diphtheria and tetanus toxoids and whole cell pertussis vaccine and other tetanus toxoid–containing vaccines; measles, mumps, and rubella (MMR) vaccines; Haemophilus influenzae type B vaccine; hepatitis B vaccine; and both inactivated and oral polio vaccines.2 The reports informed the secretary’s review of the Vaccine Injury Table. The reports have also been referenced extensively as a source of definitive scientific understanding of the evidence by Special Masters in decisions regarding injuries not listed on the Vaccine Injury Table.

The IOM was subsequently asked to review specific vaccine safety concerns in a series of reports requested by the CDC. These reports (IOM, 2001a,b, 2002a,b, 2003a,b, 2004a,b) included causality assessments similar to the previous IOM reports, but included other conclusions and recommendations regarding research, communications, and policy review.

CHARGE TO THE COMMITTEE

In 2009 HRSA requested that the IOM convene a committee of experts to review the epidemiological, clinical, and biological evidence regarding adverse health events associated with specific vaccines covered by the VICP. The committee was charged with developing a consensus report with conclusions on the evidence bearing on causality and the evidence regarding the biological mechanisms that underlie specific theories for how a specific vaccine is related to a specific adverse event. The vaccines to be reviewed include varicella zoster vaccine, influenza vaccines (but not 2009 H1N1 vaccine), hepatitis B vaccine, human papillomavirus vaccine, tetanus-containing vaccines other than those containing the whole cell pertussis component, MMR vaccine, hepatitis A vaccine, and meningococcal vaccines. It is expected that the report will provide the scientific basis for review and adjudication of claims of vaccine injury by the VICP.

HRSA presented a list of specific adverse events for the committee to review (see Table 1-1). The selection criteria were described at the first committee meeting (Johann-Liang, 2009) as including the vast majority of adverse events in the claims for compensation. The committee added adverse events to the list if it identified epidemiologic studies or case reports

___________

1 Adverse events are distinguished from adverse effects in that an event is something that occurs but may not be causally associated, whereas an adverse “effect” implies causation. All adverse effects are adverse events, but not all adverse events are adverse effects.

2 Vaccines are included in the VICP if they are recommended by the CDC for routine admin istration in children and are subject to an excise tax. Adults who experience an adverse reaction to one of these “childhood” vaccines are also covered by the program.

Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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TABLE 1-1 Adverse Events Included in the Vaccine Chapters


Adverse Evenr MMR Vaccine Chapter 4 Varicella Vaccine Chapter 5 Influenza Vaccine Chapter 6 Hepatitis A Vaccine Chapter 7 Hepatitis B Vaccine Chapter 8 HPV Vaccine Chapter 9 DT-, TT-,
and aP-Containing
Vaccines
Chapter 10
Meningococcal Vaccines
Chapter 11
Injected-Related
Events Chapter 12

Disseminated Oka VZV without Other Organ Involvement
Disseminated Oka VZV with Subsequent Infection) Resulting in Pneumonia, Meningitis, or Hepatitis
Vaccine Strain Viral Reactivation without Other Organ Involvement
Vaccine Strain Viral Reactivation with Subsequent Infection Resulting in Meningitis or Encephalitis
Measles Inclusion Body Encephalitis
Encephalitis
Encephalopathy
Infantile Spasms
Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
×

Adverse Evenr MMR Vaccine Chapter 4 Varicella Vaccine Chapter 5 Influenza Vaccine Chapter 6 Hepatitis A Vaccine Chapter 7 Hepatitis B Vaccine Chapter 8 HPV Vaccine Chapter 9 DT-, TT-,
and aP-Containing
Vaccines
Chapter 10
Meningococcal Vaccines
Chapter 11
Injected-Related
Events Chapter 12

Seizures
Meningitis
Cerebellar Ataxia
Ataxia
Autism
Acute Disseminated Encephalomyelitis
Transverse Myelitis
Optic Neuritis
Neuromyelitis Optica
Multiple Sclerosis
First Demy el ina ting Event
Guillain-Barre Syndrome
Chronic Inflammatory Disseminated Polyneuropathy
Opsoclonus Myoclonus Syndrome
Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
×
Bell's Palsy
Brachial Neuritis
Amyotrophic Lateral Sclerosis
Small Fiber Neuropathy
Anaphylaxis
Chronic Urticaria
Serum Sickness
Asthma
Erythema Nodosum
Systemic Lupus Erythematous
Vasculitis
Polyarteritis Nodosa
Psoriatic Arthritis
Reactive Arthritis
Rheumatoid Arthritis
Juvenile Idiopathic Arthritis
Arthropathy (Arthralgia and Arthritis)
Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
×

Adverse Evenr MMR Vaccine Chapter 4 Varicella Vaccine Chapter 5 Influenza Vaccine Chapter 6 Hepatitis A Vaccine Chapter 7 Hepatitis B Vaccine Chapter 8 HPV Vaccine Chapter 9 DT-, TT-,
and aP-Containing
Vaccines
Chapter 10
Meningococcal Vaccines
Chapter 11
Injected-Related
Events Chapter 12

Type 1 Diabetes
Hepatitis (Autoimmune)
Myocarditis
Pancreatitis
Hepatitis
Thromboembolic Events
Stroke
Hypercoagulable States
Myocardial Infarction
Chronic Fatigue Syndrome
Chronic Headaches
Fibromyalgia
Sudden Infant Death Syndrome
Hearing Loss
All-Cause Mortality
Oculorespiratory Syndrome
Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
×
Thrombocytopenia
HImmune Thrombocytopenic Purpura
Complex Regional Pain Syndrome
Deltoid Bursitis
Syncope

NOTE: Adverse events indicated by “❍” were added to the list by the committee.

Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
×

for an adverse event not originally assigned by HRSA. These additions were all-cause mortality and seizures following influenza vaccine; optic neuritis following MMR, influenza, hepatitis B, and diphtheria, tetanus, and pertussis (DTaP) vaccines; neuromyelitis optica and meningitis following MMR vaccine; erythema nodosum following hepatitis B vaccine; and stroke and small fiber neuropathy following varicella vaccine.

The committee was also tasked with addressing, as time and evidence allowed, general considerations. These included: underlying (susceptible) populations, “immune dysfunction,” vaccine administration issues, appropriate time intervals for anaphylaxis and autoimmune diseases, and sequential vaccination issues. The committee addressed some of these, as described in Chapters 412. It is important to note that the committee was not tasked with assessing the benefits (effectiveness) of vaccines or any policy issues related to vaccination. The task is clearly focused on an assessment only of the risk of vaccines.

COMMITTEE PROCESS

The committee was composed of individuals with expertise in pediatrics, internal medicine, neurology, immunology, immunotoxicology, neurobiology, rheumatology, epidemiology, biostatistics, and law. Appendix F includes biographical sketches of the committee members. The committee met eight times between April 2009 and March 2011. The committee held open sessions at three of these meetings. Appendix G includes agendas of these open meetings. The committee’s methodology and approach to their task is described in Chapter 2.

OUTLINE OF THE REPORT

Chapter 2 details the committee’s methodology. Chapter 3 discusses generally possible mechanisms of vaccine injury. Chapters 411 present the evidence reviewed by the committee for each of the eight vaccines covered and the conclusions it reaches. Chapter 12 presents causality assessments for adverse events that can occur with any injected vaccine regardless of the vaccine antigen and components. The committee discusses some special considerations of its work in Chapter 13.

REFERENCES

CDC (Centers for Disease Control and Prevention). 2001. Vaccinia (smallpox) vaccine recommendations of the Advisory Committee on Immunization Practices (ACIP), 2001. Morbidity & Mortality Weekly Report 50(RR-10).

CDC. 2008. Human rabies prevention. Morbidity & Mortality Weekly Report 57(RR-3):1-36.

Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
×

CDC. 2010. History of vaccine safety. http://www.cdc.gov/vaccinesafety/Vaccine_Monitoring/history.html (accessed August 1, 2011).

Guyer, B., M. A. Freedman, D. M. Strobino, and E. J. Sondik. 2000. Annual summary of vital statistics: Trends in the health of Americans during the 20th century. Pediatrics 106(6):1307-1317.

HHS (U.S. Department of Health and Human Services). 2010. Deaths: Final data for 2007. National Vital Statistics Reports 58(19).

IOM (Institute of Medicine). 1991. Adverse effects of pertussis and rubella vaccines: A report of the committee to review the adverse consequences of pertussis and rubella vaccines. Washington, DC: National Academy Press.

IOM. 1994. Adverse events associated with childhood vaccines: Evidence bearing on causality. Washington, DC: National Academy Press.

IOM. 2001a. Immunization safety review: Measles-mumps-rubella vaccine and autism. Washington, DC: National Academy Press.

IOM. 2001b. Immunization safety review: Thimerosal-containing vaccines and neuro-developmental disorders. Washington, DC: National Academy Press.

IOM. 2002a. Immunization safety review: Hepatitis B vaccine and demyelinating neurological disorders. Washington, DC: The National Academies Press.

IOM. 2002b. Immunization safety review: Multiple immunizations and immune dysfunction. Washington, DC: National Academy Press.

IOM. 2003a. Immunization safety review: SV40 contamination of polio vaccine and cancer. Washington, DC: The National Academies Press.

IOM. 2003b. Immunization safety review: Vaccinations and sudden unexpected death in infancy. Washington, DC: The National Academies Press.

IOM. 2004a. Immunization safety review: Influenza vaccines and neurological complications. Washington, DC: The National Academies Press.

IOM. 2004b. Immunization safety review: Vaccines and autism. Washington, DC: The National Academies Press.

Johann-Liang, R. 2009. Charge to the Institute of Medicine Committee to Review Adverse Effects of Vaccines. Paper read at the Meeting of the Institute of Medicine Committee to Review of Adverse Effects of Vaccines, Washington, DC.

Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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Suggested Citation:"1 Introduction." Institute of Medicine. 2012. Adverse Effects of Vaccines: Evidence and Causality. Washington, DC: The National Academies Press. doi: 10.17226/13164.
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In 1900, for every 1,000 babies born in the United States, 100 would die before their first birthday, often due to infectious diseases. Today, vaccines exist for many viral and bacterial diseases. The National Childhood Vaccine Injury Act, passed in 1986, was intended to bolster vaccine research and development through the federal coordination of vaccine initiatives and to provide relief to vaccine manufacturers facing financial burdens. The legislation also intended to address concerns about the safety of vaccines by instituting a compensation program, setting up a passive surveillance system for vaccine adverse events, and by providing information to consumers. A key component of the legislation required the U.S. Department of Health and Human Services to collaborate with the Institute of Medicine to assess concerns about the safety of vaccines and potential adverse events, especially in children.

Adverse Effects of Vaccines reviews the epidemiological, clinical, and biological evidence regarding adverse health events associated with specific vaccines covered by the National Vaccine Injury Compensation Program (VICP), including the varicella zoster vaccine, influenza vaccines, the hepatitis B vaccine, and the human papillomavirus vaccine, among others. For each possible adverse event, the report reviews peer-reviewed primary studies, summarizes their findings, and evaluates the epidemiological, clinical, and biological evidence. It finds that while no vaccine is 100 percent safe, very few adverse events are shown to be caused by vaccines. In addition, the evidence shows that vaccines do not cause several conditions. For example, the MMR vaccine is not associated with autism or childhood diabetes. Also, the DTaP vaccine is not associated with diabetes and the influenza vaccine given as a shot does not exacerbate asthma.

Adverse Effects of Vaccines will be of special interest to the National Vaccine Program Office, the VICP, the Centers for Disease Control and Prevention, vaccine safety researchers and manufacturers, parents, caregivers, and health professionals in the private and public sectors.

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