Clinical and serologic effects of Alice strain live attenuated influenza A (H3N2) virus vaccine in an adult population

A clinical trial with Alice/R-75 strain, live attenuated serum inhibitor-resistant intranasal bivalent influenza A/B vaccine

A clinical trial was conducted with Alice/R-75 strain live attenuated intranasal influenza A/B vaccine. With double blind control 88 adult volunteers were administered 2 doses of Alice/R-75 vaccine, 93 volunteers received one dose of Alice/R-75 vaccine and one dose placebo solution and 94 subjects were administered 2 doses of placebo solution. Twenty-three other subjects received Alice strain monovalent influenza A vaccine. For comparison, data from 21 subjects who received monovalent intranasal R-75 strain influenza B in two doses is included. The vaccine was generally well tolerated. Four-fold serum hemagglutination-inhibiting (HAI) antibody titer rises to A/England/42/72 occurred in 39% of the monovalent Alice strain vaccines; in contrast 18% of those given 2 doses of bivalent Alice/R-75 vaccine and 11% of those given 1 dose of bivalent vaccine had similar four-fold HAI antibody titer rises. HAI antibody titer rises to influenza B/Hong Kong/72 occurred in 38% of R-75 strain monovalent vaccinees, 14% of Alice/R-75 2-dose vaccinees and 11% of Alice/R-75 one dose vaccinees. An epidemic of influenza at onset of the study made evaluation of the efficacy of the vaccine impossible.

Clinical and serologic effects of live attenuated serum inhibitor-resistant influenza B vaccine in seronegative adults

The clinical effects, nasal and serum antibody responses, and virus excretion of a live attenuated serum inhibitor-resistant influenza B virus vaccine, R75, was evaluated in 43 seronegative healthy adults by a random double-blind study. Symptom responses were minimal and were not significantly different between vaccine and placebo groups. No fevers, abnormalities in physical examination or laboratory testing developed during 4 weeks of observation. Among vaccinees, 10 (48%) developed serum hemagglutination-inhibition (HI) antibodies, 16 (76%) developed serum neutralization (N) antibodies and 4 (19%) developed nasal N antibodies. The GMT responses from study day 0 to day 28 were 4.0 to 10.4 for serum HI, 1.8 to 9.8 for serum N, and 1.0 to 1.4 for nasal N. There were no significant titer changes in the placebo group. No virus excretion was detected. Although there are some questions concerning the relationship of antibody levels to protection, the low antibody responses in this study are an indication that R75 is not sufficiently immunogenic.