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.
The prevalence of childhood asthma has been increasing in the past two decades in the United States. Some have suggested that this increase may be due to vaccinations, although recent studies do not support that hypothesis.
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.