Evaluation of trivalent, live, cold-adapted (CAIV-T) and inactivated (TIV) influenza vaccines in prevention of virus infection and illness following challenge of adults with wild-type influenza A (H1N1), A (H3N2), and B viruses.
Trivalent, live, cold-adapted influenza vaccine (CAIV-T) is highly effective in the prevention of influenza in children, and a variety of monovalent and bivalent cold-adapted influenza vaccines have been efficacious in adults. In order to determine the efficacy of CAIV-T in healthy adults, we administered CAIV-T, trivalent inactivated influenza vaccine (TIV) or placebo to 103 adults in randomized double-blind fashion, and then challenged those subjects who had pre-screening serum hemagglutination-inhibition antibody titers of 1:8 or less with wild-type influenza viruses corresponding to the strains contained in the vaccine. CAIV-T was well tolerated. Upon challenge with wild-type influenza virus, laboratory documented influenza illness (respiratory symptoms with either isolation of wild-type influenza virus from nasal secretions or 4-fold and/or greater HAI antibody response to challenge) occurred in 14/31 (45%) placebo recipients, 4/32 (13%) TIV recipients, and 2/29 (7%) CAIV-T recipients. The estimated protective efficacy of CAIV-T was therefore 85% and of TIV was 71%. These results are consistent with those of previous studies using monovalent preparations of cold-adapted influenza vaccine in this model, and indicate that CAIV-T will be an effective means to prevent influenza illness in adults.
Treanor
J J
JJ
Infectious Diseases Unit, Department of Medicine, University of Rochester School of Medicine, Box 689, 601 Elmwood Avenue, Rochester, NY 14642, USA. john_treanor@urmc.rochester.edu
Kotloff
K
K
Betts
R F
RF
Belshe
R
R
Newman
F
F
Iacuzio
D
D
Wittes
J
J
Bryant
M
M
D000281:Administration, Intranasal; D000328:Adult; D003080:Cold Temperature; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D053122:Influenza A Virus, H3N2 Subtype; D009980:Influenza A virus / Q000276:immunology*; D009981:Influenza B virus / Q000276:immunology*; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000517:prevention & control; D007273:Injections, Intramuscular; D017778:Vaccines, Combined / Q000276:immunology; D014614:Vaccines, Synthetic
D007252:Influenza Vaccines; D017778:Vaccines, Combined; D014614:Vaccines, Synthetic