Perhaps the greatest success story in public health is the reduction of infectious diseases resulting from the use of vaccines. Routine immunization has eradicated smallpox from the globe and led to the near elimination of wild polio virus.
Vaccines have reduced some preventable infectious diseases to an all-time low, and now few people experience the devastating effects of measles, pertussis, and other illnesses. Prior to approval by the Food and Drug Administration (FDA), vaccines are tested extensively by scientists to ensure they are effective and safe.
Vaccines are the best defense we have against infectious diseases; however, no vaccine is 100% safe or effective. Differences in the way individual immune systems react to a vaccine account for rare occasions when people are not protected following immunization or when they experience side effects.
As the incidence of infectious diseases continues to decline, some people have become less interested in the consequences of preventable illnesses like diphtheria and tetanus. Instead, they have become increasingly concerned about the risks associated with vaccines. After all, vaccines are given to healthy individuals, many of whom are children, and therefore a high standard of safety is required.
Since vaccination is such a common and memorable event, any illness following immunization may be attributed to the vaccine. While some of these reactions may be caused by the vaccine, many of them are unrelated events that occur after vaccination by coincidence. Therefore, the scientific research that attempts to distinguish true vaccine side effects from unrelated, chance occurrences is crucial. This knowledge is necessary to maintain public confidence in immunization programs.
As science continues to advance, we strive to develop safer vaccines and improve delivery to protect ourselves against disease more effectively. This overview focuses on vaccine research, how vaccines are licensed, how safety is monitored, and how risks are communicated to the public
Thursday, March 12, 2009
Why It’s Important to Monitor Vaccine Safety
John Iskander, MD, MPH, acting director, Immunization Safety Office, and Robert T. Chen, MD, MA, blood safety specialist, Epidemiology Branch, NCHHSTP,
wrote a chapter in the new book
Infectious Disease Surveillance to explain why it is important to monitor vaccine safety.
Rare Reactions.
The most important reason is to detect rare reactions. Although vaccines are tested extensively before they are licensed for use in the United States, not enough people are included in the tests to detect reactions that happen only rarely. If serious reactions are found when the vaccine is in widespread use, the vaccine may be withdrawn.
Higher Risk Groups.
Vaccine safety monitoring also makes sure new vaccines are safe for groups such as the elderly, those with chronic medical conditions, and pregnant women. Vaccine trials may deliberately exclude members of these groups.
Public Confidence in Vaccines.
Monitoring vaccine safety also helps to maintain public confidence needed to keep enough people vaccinated to prevent disease outbreaks.
How We Know If Vaccines Are Safe
Vaccine safety cannot be measured directly. Instead, it is estimated by the number of "adverse events" reported. An adverse event is "... a medical incident that takes place after an immunization ... and is believed to be caused by the immunization." Adverse events include—
True reactions to the vaccine.
Events that would have occurred even if the person had not been vaccinated (unrelated coincidences).
Reactions related to mistakes in vaccine preparation, handling, or administration.
Events that cannot be related directly to the vaccine; their cause is unknown.
A formal scientific study usually is required to distinguish between coincidences and true reactions. It is rarely possible to say for sure whether a vaccine caused a specific adverse event.
wrote a chapter in the new book
Infectious Disease Surveillance to explain why it is important to monitor vaccine safety.
Rare Reactions.
The most important reason is to detect rare reactions. Although vaccines are tested extensively before they are licensed for use in the United States, not enough people are included in the tests to detect reactions that happen only rarely. If serious reactions are found when the vaccine is in widespread use, the vaccine may be withdrawn.
Higher Risk Groups.
Vaccine safety monitoring also makes sure new vaccines are safe for groups such as the elderly, those with chronic medical conditions, and pregnant women. Vaccine trials may deliberately exclude members of these groups.
Public Confidence in Vaccines.
Monitoring vaccine safety also helps to maintain public confidence needed to keep enough people vaccinated to prevent disease outbreaks.
How We Know If Vaccines Are Safe
Vaccine safety cannot be measured directly. Instead, it is estimated by the number of "adverse events" reported. An adverse event is "... a medical incident that takes place after an immunization ... and is believed to be caused by the immunization." Adverse events include—
True reactions to the vaccine.
Events that would have occurred even if the person had not been vaccinated (unrelated coincidences).
Reactions related to mistakes in vaccine preparation, handling, or administration.
Events that cannot be related directly to the vaccine; their cause is unknown.
A formal scientific study usually is required to distinguish between coincidences and true reactions. It is rarely possible to say for sure whether a vaccine caused a specific adverse event.
Vaccine Safety Information for Parents
Vaccines are held to the highest standard of safety. The United States currently has the safest, most effective vaccine supply in history. Years of testing are required by law before a vaccine can be licensed. Once in use, vaccines are continually monitored for safety and efficacy.
Immunizations, like any medication, can cause adverse events.
However, a decision not to immunize a child also involves risk.
It is a decision to put the child and others who come into contact with him or her at risk of contracting a disease that could be dangerous or deadly. Consider measles. One out of 30 children with measles develops pneumonia. For every 1,000 children who get the disease, one or two will die from it.
Thanks to vaccines, we have few cases of measles in the U.S. today. However, the disease is extremely contagious, and each year dozens of cases are imported from abroad into the U.S., threatening the health of people who have not been vaccinated and those for whom the vaccine was not effective.
The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) continually work to make already safe vaccines even safer. In the rare event that a child is injured by a vaccine, he or she may be compensated through the National Vaccine Injury
Compensation Program (VICP) or call 1-800-338-2382.
Immunizations, like any medication, can cause adverse events.
However, a decision not to immunize a child also involves risk.
It is a decision to put the child and others who come into contact with him or her at risk of contracting a disease that could be dangerous or deadly. Consider measles. One out of 30 children with measles develops pneumonia. For every 1,000 children who get the disease, one or two will die from it.
Thanks to vaccines, we have few cases of measles in the U.S. today. However, the disease is extremely contagious, and each year dozens of cases are imported from abroad into the U.S., threatening the health of people who have not been vaccinated and those for whom the vaccine was not effective.
The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) continually work to make already safe vaccines even safer. In the rare event that a child is injured by a vaccine, he or she may be compensated through the National Vaccine Injury
Compensation Program (VICP) or call 1-800-338-2382.
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