The U.S. Food and Drug Administration (FDA) on November 22, 2013 approved the first H5N1 avian influenza (bird flu) adjuvanted vaccine for adults. An adjuvant is a substance added to a vaccine that stimulates the body's immune response to an inactivated virus. The vaccine, pandemic Influenza A (H5N1) Virus Monovalent Vaccine, Adjuvanted (also known as Q-Pan H5N1 influenza vaccine and by the brand name Pumarix™ in Europe) was developed by GlaxoSmithKline. Testing showed the vaccine produced a sufficient immune response to lower the risk of catching bird flu, with minimal side effects. See also: Avian influenza (bird flu); Epidemic; Influenza; Vaccination

The vaccine will be stored in the U.S. national stockpile for use in the event of a flu outbreak. If needed, the vaccine will be given in two doses, 21 days apart.

The H5N1 influenza virus has become the focus of many epidemiologists concerns because it bears some similarities to the strain of H1N1 flu virus that caused the Spanish flu pandemic of 1918–1919, one of the deadliest in history, which killed between 50 million and 100 million people worldwide. See also: H1N1 influenza