Objective It is well known that vaccines and national immunization program have helped to protect peoples,especially the children from infectious diseases such as smallpox,polio,measles and pertussis across the globe.However,adverse events may occur following immunization,which may lead to public concerns about the vaccine safety.Such concerns may threaten the success of an immunization program.Prompt and appropriate responses to adverse events can help to avoid the negative impacts to the National Immunization Program of China.