Programs that collect reports of adverse side effects following administration of new vaccines and store them in the Vaccine Adverse Event Reporting System (VAERS), a national vaccine safety surveillance program co-sponsored by the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC). VAERS collects and analyzes information from reports of possible side effects after the administration of U.S. licensed vaccines, and welcomes reports from all concerned individuals including patients, parents, health care providers, pharmacists and vaccine manufacturers. The most common side effects after vaccination are mild and are a sign the body is starting to build immunity against a disease. They include pain, swelling, or redness where the shot was given, mild fever, chills, feeling tired, headache, muscle and joint aches as well as fainting (which can happen after any medical procedure). The information may be made available to the public with the caveat that a causal relationship has not been established and the information in the reports may not have been medically confirmed.