Science & tech spotlight : vaccine safety Anti-Vaccination Movement Government Regulation Safety Vaccine-Preventable Diseases -- psychology Vaccines -- adverse effects What is it? A vaccine is generally considered safe when the benefits of protecting an individual from disease outweigh the risks from potential side effects (fig. 1). The most common side effects stem from the body’s immune reaction and include swelling at the injection site, fever, and aches. In rare cases, some vaccines may cause more severe side effects. For example, the vaccine for rotavirus—a childhood illness that can cause severe diarrhea, dehydration, and even death—can cause intestinal blockage in one in 100,000 recipients. However, the vaccine is still administered because this very rare side effect is outweighed by the vaccine’s benefits: it saves lives and prevents an estimated 40,000 to 50,000 childhood hospitalizations in the U.S. each year. The two messenger RNA (mRNA) vaccines authorized for COVID19—a disease that contributed to more than 415,000 American deaths between January 2020 and January 2021—can cause severe allergic reactions. However, early safety reporting found that these reactions have been extremely rare, with only about five cases per 1 million recipients, according to data from January 2021 reports by the Centers for Disease Control and Prevention. In general, side effects from vaccines are less acceptable to the public than side effects from treatments given to people who already have a disease. Washington, DC : United States Government Accountability Office, February 2021 United States. Government Accountability Office, issuing body. United States. Congress, issuing body. Technical Report Text Illustrations 1 online resource (1 PDF file (2 unnumbered pages)) nlm:nlmuid-9918317781806676-pdf 9918317781806676 http://resource.nlm.nih.gov/9918317781806676 English United States The National Library of Medicine believes this item to be in the public domain. https://creativecommons.org/publicdomain/mark/1.0