Liposomal influenza vaccine

This trivalent liposomal influenza vaccine consists of purified influenza haemagglutinin inserted into a membrane of phosphatidylcholine and phosphatidylethanolamine. It contains 15microg of haemagglutinin per viral strain per dose. The vaccine is immunogenic in the elderly, in younger adults and in children and adolescents with or without cystic fibrosis. Seroconversion rates were significantly higher with the liposomal vaccine than with a subunit vaccine for 3 of 3 and 2 of 3 strains in 2 published studies. Seroconversion occurred in a significantly greater number of participants receiving the liposomal vaccine than in those receiving a whole virus vaccine for all 3 strains in 1 study. Seroprotection rates were significantly better with the liposomal vaccine than with a subunit vaccine for 2 of 3 and 1 of 3 strains in 2 trials, and greater than with a whole virus vaccine for 2 of 3 strains in 1 trial. In a study in children with cystic fibrosis, a single dose of the liposomal vaccine was reported to have greater immunogenicity than 2 half doses (statistical analysis not performed). Local adverse reactions such as pain at the injection site, local induration, redness and swelling are transient and usually mild. Liposomal influenza vaccine did not induce a mean antiphospholipid antibody response in elderly volunteers.