Global Vaccine Safety

Information for health-care workers - managing adverse events

Last updated: 9 April 2009


Vaccines are designed to provoke a reaction in the body. If it were not so, they would not produce the reaction in the immune system that provides the protection from disease which is sought. In addition to the desired reaction, all vaccines produce some degree of unwanted reaction. The vast majority of these are trivial and harmless. Some are more noticeable and annoying. A very small number are serious and potentially life threatening. But the benefits of protection afforded by the vaccine always far exceed the slight risk of a reaction. If this were not so, WHO would not promote their use. All the vaccines recommended by WHO are chosen because of their clearly demonstrated track record for safety and effectiveness. In addition, specific vaccines purchased and provided by UNICEF or other UN agencies have been carefully assessed by WHO to ensure they meet its standards for quality and production.