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    Vaccine Safety Monitoring

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    CDC monitors the safety of vaccines by:

    • Performing high-quality vaccine safety research.
    • Making determinations about whether vaccines caused reactions in certain cases and helping to learn about preventable risk factors.
    • Identifying vaccine adverse events through public health surveillance.

    CDC’s Immunization Safety Office conducts four primary vaccine safety activities:

    Vaccine Adverse Event Reporting System (VAERS)

    An early warning system that helps CDC and FDA monitor problems following vaccination.  Anyone can report suspected vaccine reactions and issues to VAERS.

    Clinical Immunization Safety Assessment (CISA) Project

    A partnership between CDC and several medical centers that conduct clinical research on vaccine-associated health risks in certain groups of people.

    Vaccine Safety Datalink (VSD)

    A collaboration between CDC and several health care organizations that allows ongoing monitoring and proactive searches of vaccine-related data.

    Emergency Preparedness for Vaccine Safety

    In the event of a disease outbreak in which a mass vaccination campaign is needed, CDC activates emergency preparedness activities to ensure that vaccines remain safe.

    Related Links
    • How Vaccines are Tested, Licensed, and Monitored for Safety
    • Reporting Adverse Events
    • Understanding Side Effects and Adverse Events
    • Vaccine Safety Research
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    Page last reviewed: August 28, 2020
    Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Healthcare Quality Promotion (DHQP)
    homeVaccine Safety
    • Safety Information by Vaccineplus icon
      • Chickenpox (Varicella) Vaccines
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        • Questions about HPV Vaccine Safety
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        • CDC Study (2010 ) on Thimerosal and Risk of Autism
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        • GBS and Menactra Vaccine FAQs
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        • Narcolepsy Following Pandemrix Influenza Vaccination in Europe
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          • Frequently Asked Questions and Troubleshooting
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