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

Post-Polio Syndrome, Vaccine-Associated Paralytic Polio and Poliomyelitis Elimination

In 2005, an unimmunized child was reported from Minnesota with poliovirus infection. At the time of this study, three other unimmunized children in the same community had also been identified as being infected. What was the origin of these infections?


Vaccine Components

Aluminum Adjuvants in Vaccines

Some vaccines contain chemicals called adjuvants to help stimulate the production of immunity against the vaccine ingredients, making the vaccine more effective. In the United States, aluminum salts have frequently been incorporated as adjuvants in vaccines.