Abstract | BACKGROUND: METHODS: Nasal IgA responses were assessed using data from 3 prospective, 2-year, randomized studies comparing LAIV with placebo in children 6-36 months of age. In each study, samples were collected in a subset of patients; a new cohort was enrolled each year. Ratios of strain-specific nasal IgA to total nasal IgA were calculated and prevaccination to postvaccination geometric mean fold-rises (GMFRs) were evaluated. Mean postvaccination IgA ratios were compared for subjects with and without confirmed influenza illness by study and in pooled analyses. RESULTS: Across studies, a higher percentage of children receiving LAIV had a ≥ 2-fold increase in strain-specific IgA ratio compared with placebo recipients. GMFRs after LAIV in years 1 and 2 ranged from 1.2 to 6.2, compared with 0.5-2.2 among placebo recipients. Similar responses were observed in subjects who were baseline seronegative and seropositive based on serum hemagglutination inhibition antibody titers. In years 1 and 2, the mean postvaccination strain-specific to total IgA ratio was 3.1-fold (P<0.01) and 2.0-fold (P<0.03) higher among LAIV recipients with no evidence of culture-confirmed influenza illness compared with LAIV recipients who developed culture-confirmed influenza illness; a similar and consistent trend was observed for each individual study and type/subtype. CONCLUSIONS: The current analysis demonstrates that nasal IgA contributes to the efficacy of LAIV and can provide evidence of vaccine-induced immunity. However, the inherent heterogeneity in nasal antibody levels and variability in nasal specimen collection hinders the precise evaluation of mucosal antibody responses. Other studies have demonstrated that LAIV-induced immunity is also partially explained by T-cell immunity, serum antibody responses, and innate immunity, consistent with the multi-faceted nature of immunity induced by wild-type influenza infection and other live virus vaccines.
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Authors | Christopher S Ambrose, Xionghua Wu, Taff Jones, Raburn M Mallory |
Journal | Vaccine
(Vaccine)
Vol. 30
Issue 48
Pg. 6794-801
(Nov 06 2012)
ISSN: 1873-2518 [Electronic] Netherlands |
PMID | 23000125
(Publication Type: Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)
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Copyright | Copyright © 2012 Elsevier Ltd. All rights reserved. |
Chemical References |
- Immunoglobulin A
- Influenza Vaccines
- Placebos
- Vaccines, Attenuated
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Topics |
- Child, Preschool
- Humans
- Immunity, Mucosal
- Immunoglobulin A
(immunology)
- Infant
- Influenza Vaccines
(administration & dosage, immunology)
- Influenza, Human
(immunology, prevention & control)
- Nasal Mucosa
(immunology)
- Placebos
(administration & dosage)
- Prospective Studies
- Vaccines, Attenuated
(administration & dosage, immunology)
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