title: Estimating efficacy of trivalent, cold-adapted, influenza virus vaccine (CAIV-T) against influenza A (H1N1) and B using surveillance cultures.
abstract: The authors report on a community-based, nonrandomized, open-label study, conducted during the 2000-2001 influenza season in Temple-Belton, Texas, of the protective effectiveness of trivalent, cold-adapted, influenza virus vaccine (CAIV-T) in children aged 18 months-18 years. The dominant circulating strains in 2000-2001 were influenza A/New Caledonia/20/99 (H1N1) and influenza B/Sichuan/379/99. Children had access to CAIV-T during the 1998-1999, 1999-2000, and 2000-2001 influenza seasons. The vaccine included influenza A/Sydney/5/97 (H3N2) and B/Beijing/184/93-like (B/Ann Arbor/l/94) strains in all three seasons. The vaccine included A/Beijing/262/95 (H1N1) in 1998-1999 and 1999-2000, which was replaced by A/New Caledonia/20/99 (H1N1) in 2000-2001. When medically attended acute respiratory illness (MAARI) was used as the outcome, the protective effectiveness for children vaccinated in 2000 was 18% (95% confidence interval (CI): 11, 25). Based on a combination of a validation sample of surveillance cultures and the MAARI outcome, protective efficacy against combined influenza A (H1N1) and B was 79% (95% CI: 51, 91). The efficacy estimate, after accounting for missing influenza culture status, against influenza A (H1N1) alone was 92% (95% CI: 42, 99) and against a new variant of influenza B alone was 66% (95% CI: 9, 87). CAIV-T provides substantial protection against a mixture of influenza A (H1N1) and B. Results demonstrate the powerful potential of using validation sets for outcomes in vaccine field studies.
authors.affiliation: Department of Biostatistics, Rollins School of Public Health, Emory University, 1518 Clifton Road NE, Atlanta, GA 30322, USA. mehallo@sph.emoryedu
authors.forename: M Elizabeth
authors.initials: ME
authors.lastname: Halloran
authors.forename: Ira M
authors.initials: IM
authors.lastname: Longini
authors.forename: Manjusha J
authors.initials: MJ
authors.lastname: Gaglani
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Piedra
authors.forename: Haitao
authors.initials: H
authors.lastname: Chu
authors.forename: Gayla B
authors.initials: GB
authors.lastname: Herschler
authors.forename: W Paul
authors.initials: WP
authors.lastname: Glezen
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D009980:Influenza A virus / Q000276:immunology*; D009981:Influenza B virus / Q000276:immunology*; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D014611:Vaccination
chemical_list: D007252:Influenza Vaccines