Comparative trial of large-particle aerosol and nose drop administration of live attenuated influenza vaccines.

Healthy adult subjects (n = 198) were randomized to receive bivalent cold-adapted (ca) influenza A vaccine containing 10(7.4) TCID50 each of A/Kawasaki/9/86 (H1N1) and A/Los Angeles/2/87 (H3N2) by either nose drops (ND) or large-particle aerosol (LPA). All subjects had received monovalent inactivated influenza B vaccine intramuscularly in the previous year. Ninety percent of LPA recipients and 82% of ND recipients preferred intranasal administration to their previous experience with intramuscular vaccine. Twenty-six (27%) of 98 LPA recipients and 47 (49%) of 97 ND recipients reported swallowing vaccine (P = .008). Fever was observed uncommonly (< or = 5%), and incidence of respiratory symptoms was comparable between groups. Fourfold or greater hemagglutination antibody response to at least one of the influenza A vaccine viruses was significantly more frequent after LPA (64%) than ND vaccination (43%; P = .005). LPA administration of ca influenza to the nasopharynx was well tolerated, safe, and more immunogenic than ND delivery.