Objective: Assess safety and immunogenicity of increasing doses of intranasally delivered CAIV-T in children. Design: Double-blind, placebo controlled, randomized trial. Population: Healthy children(n=356) ages 18 to 71 mos from 5 med. centers, 4 U.S. & 1 Chilean. Vaccine: CAIV-T with 104, 105, 106, or 107 TCID50 each of A/Johannesburg/33/94-like (H3N2), A/Texas/36/91-like (HINI), and B/Panama/45/90-like reassortants. CAIV-T or placebo (allantoic fluid) were administered as either 0.5 cc intranasal drops or spray. Measurements: Safety and reactinogenicity diaries were kept for 10 days post-vaccination. Subjects had a study nurse visit on post-vac. days 1, 4 and 10 for diary review and nasal culture for vaccine virus shedding. Sera for vaccine type hemagglutination inhibition HAI antibodies (Ab) were collected pre and 42 days post-vaccination. Results: There were no significant differences in% fever, irritability, cough, rhinorrhea, or pharyngitis between CAIV-T and placebo recipients at any dose. There were no significant differences in HAI responses or vaccine shedding between those subjects who received CAIV-T as drops or spray at any dose. In susceptibles (pre HAI ≤ 1:4) who received 107 TCID50 of CAIV (drops or spray), the% with ≥ 4-fold rise in HAI Ab and% with vaccine shedding are shown in the table. HAI response to H1N1 were low (0-16%) at all doses.
After the trial, a frozen CAIV-T vial was tested and contained 107 TCID50 of all 3 serotypes.
