The National Network for Immunization Information (NNii) provides up-to-date, science-based information to healthcare professionals, the media, and the public: everyone who needs to know the facts about vaccines and immunization.

Vaccine Safety

Vaccine Adverse Event Reporting System

The Vaccine Adverse Event Reporting System (VAERS) is a national system for reporting possible adverse reactions or side effects after any US-licensed vaccine. This article explains how VAERS works and describes its strenghts and limitations.

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Thimerosal-Mercury

Mercury in Vaccines

This article answers the most frequently asked questions about thimerosal and its use as a preservative in vaccines.

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