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Monitoring Vaccine Safety

The safety of vaccines is continuously monitored and studied by programs such as:

  • Vaccine Adverse Events Reporting System
  • Vaccine Safety Datalink project
  • National Vaccine Injury Compensation Program
  • Task Force on Safer Childhood Vaccines
  • Institute of Medicine research studies

Vaccine Adverse Events Reporting System

Sometimes a person will develop adverse signs or symptoms after receiving a vaccine. Health care providers are required to report certain adverse health effects that occur after a child is vaccinated. For example, if a child is hospitalized or dies after receiving a vaccine, this adverse event must be reported. The adverse event may have been caused by something other than the vaccine, such as an infection, a pre-existing illness, or an injury, but there is a small chance that the event was caused by a vaccine. The monitoring systems allow scientists to gather enough data to determine which events may be related to vaccines.

In 1990, the FDA and CDC established the Vaccine Adverse Events Reporting System (VAERS) so that reports could be collected and analyzed. As many as 12,000 reports have been made in a single year, and about 2,000 of these reported serious illness or death. All reports are entered into a database; FDA and CDC use the data to monitor vaccine safety and conduct research studies. However, with further examination, most of these events have been found to be unrelated to vaccines. VAERS reports do not establish cause and effect. Only large epidemiologic studies can show that the vaccine caused the adverse event.

To ensure that all relevant data are captured, the VAERS allows anyone to file a report if they suspect that their child or patient has a vaccine-related reaction. Because entries are not screened, the database contains events that are related and unrelated to vaccines. The FDA monitors VAERS to determine whether any vaccine is associated with more adverse events than would be expected due to chance.

Recently, the rotavirus vaccine was withdrawn from the market after VAERS reports identified 15 cases of severe bowel obstruction in infants who received it. VAERS data were used as a "signal" that the vaccine might be causing the problem; however subsequent epidemiological studies were necessary to establish that the vaccine was likely responsible. To date, a definite causal relationship has not been established.

VAERS Contact Information
Phone: 1-800-822-7967
Email: [email protected]

Vaccine Safety Datalink Project

Unlike the VAERS database, large linked databases allow research scientists to have access to the complete medical records of millions of people who receive vaccines. (Patient identity is not released).

In 1990, the CDC developed the Vaccine Safety Datalink Project to study rare side effects from vaccines. Four large health maintenance organizations provide the CDC with medical information on more than 6 million people. The large number of patients makes this project a powerful tool for examining the relationship between a specific vaccine and serious side effects.

Since its initiation in 1990, the Vaccine Safety Datalink Project has conducted surveillance on about 500,000 children from birth through age 6 years (2% of the U.S. population in this age group). These data were used to study the rate of Sudden Infant Death Syndrome (SIDS) after anecdotal evidence suggested a possible link to the DTP vaccine. The risk of SIDS was found to be the same for vaccinated children as for unvaccinated children enrolled in the participating health maintenance organizations. Such studies are known as "post-marketing" or "Phase IV" clinical studies because the vaccine has been approved by the FDA for marketing.

National Vaccine Injury Compensation Program

The National Vaccine Injury Compensation Program compensates people who are determined to have been injured by vaccines. Established by the National Childhood Vaccine Injury Act of 1986, it is a federal "no-fault" system compensating individuals or families of individuals who have been injured by childhood vaccines. All routinely recommended childhood vaccinations are covered by the program. People who file claims are not required to prove negligence on the part of the health care provider or the manufacturer.

A panel of experts has established a list of serious injuries that are associated with certain vaccines. This list is updated as medical research uncovers more information on the side effects of vaccines. People who file claims may qualify for compensation in three ways:

Show that the injury occurred within a certain time interval of receiving the vaccine;

  • Prove that the vaccine caused the injury; or
  • Prove that the vaccine worsened a pre-existing condition.
  • Funds accumulated from a tax on each dose of a vaccine purchased are used for the compensation awards.

Vaccines covered under the program are diphtheria, tetanus, pertussis, measles, mumps, rubella, polio, hepatitis B, Haemophilus influenzae type b, and varicella. It is anticipated that the pneumoccocal vaccine will soon be included.

NVICP Contact Information
Phone: 1-800-822-7967

Task Force on Safer Childhood Vaccines

In 1986, the Task Force on Safer Childhood Vaccines was established by the Secretary of Health and Human Services at the direction of Congress. Members of the Task Force include the Director of the National Institutes of Health, Commissioner of the Food and Drug Administration, Director of the Centers for Disease Control and Prevention, and other members of the Public Health Service.

The Task Force examines vaccine safety and makes recommendations to the Secretary of Health and Human Services for development of safe childhood vaccines and for improvements in manufacturing, processing, testing, licensing, labeling, distribution, storage, administration, adverse reaction reporting, monitoring, recalling batches, and research. Reports are published on a periodic basis. The report from January 22, 1996, is available on-line at

Institute of Medicine Reviews

The National Childhood Vaccine Injury Act established a committee at the Institute of Medicine ? a prestigious medical research organization funded by Congress to provide objective, timely, authoritative information and advice concerning health to government, the corporate sector, the professions, and the public ? to review the medical literature on health problems or injuries occurring after vaccination. The Act mandates these comprehensive reviews of vaccine-related adverse events.

The Institute of Medicine (IOM) has published the following studies on the adverse events associated with vaccines given to children:

  • Institute of Medicine. Adverse effects of pertussis and rubella vaccines. Washington, DC: National Academy Press; 1991.
  • Institute of Medicine. Adverse events associated with childhood vaccines. Washington, DC: National Academy Press; 1994.

In the fall of 2000, the IOM's Committee on Immunization Safety Review was convened to provide an independent review and assessment of increasingly prominent vaccine safety concerns. See our section on the IOM Reports for more information about this Committee's reports.

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