influenza virus vaccines

in·flu·en·za vi·rus vac·cines

influenza virus grown in embryonated eggs and inactivated, usually by the addition of formalin; both whole virus and subunit preparations containing hemagglutinins and neuraminidase are used; because of the marked and progressive antigenic variation of the influenza viruses, the strains included are regularly changed following various outbreaks of influenza to include most recently isolated epidemic strains of both type A influenza and type B influenza.