Efficacy and Safety of 1 and 2 Doses of Live Attenuated Influenza Vaccine in Vaccine-Naive Children

Efficacy and Safety of 1 and 2 Doses of Live Attenuated Influenza Vaccine in Vaccine-Naive Children

Author Bracco Neto, Humberto Autor UNIFESP Google Scholar
Farhat, Calil K. Autor UNIFESP Google Scholar
Tregnaghi, Miguel Wenceslao Google Scholar
Madhi, Shabir A. Google Scholar
Razmpour, Ahmad Google Scholar
Palladino, Giuseppe Google Scholar
Small, Margaret G. Google Scholar
Gruber, William C. Google Scholar
Forrest, Bruce D. Google Scholar
D153-P504 LAIV Study Grp Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Hosp Infantil Cordoba
Chris Hani Baragwanath Hosp
Wyeth Vaccines Res
Abstract Background: We investigated the efficacy and safety of 1 versus 2 doses of live attenuated influenza vaccine (LAIV) in influenza vaccine-naive children aged 6 to <36 months.Patients/Methods: Subjects were randomized to 1 of 4 regimens in year 1: 2 doses LAIV, 1 dose LAIV, excipient placebo, or saline placebo. in year 2, LAW recipients were to receive 1 dose of LAIV and placebo recipients were to receive saline placebo. Because of an unintended treatment allocation error in year 2, 1 block of subjects who were randomized to LAW received saline placebo and 1 block who were randomized to placebo received LAIV.Results: in year 1, vaccine efficacy versus placebo among recipients of 2 and 1 doses of LAW was 73.5% and 57.7%, respectively, against anti-genically similar strains. in year 2, absolute efficacy of a single dose of LAW was 73.6% and 65.2%, respectively, in recipients of 2 and 1 doses of LAW in year 1. Year 2 efficacy was 57.0% in subjects who received 2 doses of LAW in year 1 and placebo in year 2. Safety and tolerability of LAW were consistent with previous studies. Reactogenicity was similar between placebo groups. Seroconversion rates were significantly higher in the 2-dose versus the 1-dose LAW group in year 1 and in both LAW groups versus placebo in years 1 and 2.Conclusions: One dose of LAIV provided clinically significant protection against influenza in young children previously unvaccinated against influenza; 2 doses provided additional protection. Protection after 2 doses in year 1 persisted through a second season without revaccination. LAW excipients were not a major contributor to reactogenicity. These benefits provide support for increased use of LAW in children >= 2 years of age.
Keywords efficacy
live attenuated influenza vaccine
Language English
Date 2009-05-01
Published in Pediatric Infectious Disease Journal. Philadelphia: Lippincott Williams & Wilkins, v. 28, n. 5, p. 365-371, 2009.
ISSN 0891-3668 (Sherpa/Romeo, impact factor)
Publisher Lippincott Williams & Wilkins
Extent 365-371
Origin http://dx.doi.org/10.1097/INF.0b013e31819219b8
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000265619400001
URI http://repositorio.unifesp.br/handle/11600/31473

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