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Major Differences Between During the preparation of TIV, the vaccine viruses are made noninfectious (i.e., inactivated or killed) (91). Only subvirion and purified surface antigen preparations of TIV (often referred to as "split" and subunit vaccines, respectively) are available in the United States. TIV contains killed viruses and thus cannot cause influenza. LAIV contains live, attenuated viruses and therefore has the potential to produce mild signs or symptoms related to attenuated influenza virus infection. LAIV is administered intranasally by sprayer, whereas TIV is administered intramuscularly by injection. LAIV is currently approved only for use among healthy persons aged 5-49 years (note); TIV is approved for use among persons aged >6 months, including those who are healthy and those with chronic medical conditions (Table 3). |