Ensuring Vaccine Safety
The United States has the safest, most effective vaccine supply in its history. The nation’s longstanding vaccine safety system ensures that vaccines are as safe as possible. As new information and science become available, the system is updated and improved.
As part of these vaccine safety efforts, scientists ensure the safety of vaccines by conducting different types of studies:
- Clinical trialsexternal icon are done before a vaccine is made available. Vaccine manufacturers conduct these studies as part of the development, testing, and approval process. The Food and Drug Administration (FDA) uses the information from clinical trials to decide if a vaccine is safe, effective, and ready to be licensed for use.
- Post-licensure safety studies are conducted after a vaccine is approved and in use. These studies are part of continuous vaccine safety monitoring and often look at populations that might be underrepresented in clinical trials. Importantly, these studies can look for rare adverse events.
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Overview, History and How it WorksLearn about the history of vaccine safety, current safety programs and how they work.
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Vaccine Safety MonitoringInformation about the systems CDC uses to monitor vaccine safety.
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The Journey of Your Child’s VaccineFor parents: an infographic detailing how a new vaccine is developed, manufactured, and monitored for safety.
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Understanding Side Effects and Adverse EventsLearn about the difference between a side effect and an adverse event.
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Vaccine Safety PartnersVisit the websites of CDC’s partners in vaccine safety.
- Safety Information by VaccineThe latest safety information from CDC on the recommended U.S. vaccines
- Vaccine Safety ResearchPublished vaccine safety research from CDC’s Immunization Safety Office
- Common Questions and ConcernsAnswers to the most common questions and concerns about vaccine safety
- Vaccine Safety Information from Vaccines.govexternal iconAdditional information about vaccine safety