High Quality Content by WIKIPEDIA articles! Live attenuated influenza vaccine (LAIV) is a type of a influenza vaccine in the form of a nasal spray. It is an attenuated vaccine, unlike most influenza vaccines, which are inactivated vaccines. LAIV is administered intranasally, while inactivated vaccines are administered by intramuscular injection. Both live attenuated and inactivated vaccines are typically trivalent. That is, they contain material from three different influenza virus strains recommended by national and international public health agencies as most likely to be protective against seasonal influenza in any given year. LAIV is sold under the trade name FluMist in the United States and Fluenz in Europe.