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Efficacy and safety of 1 and 2 doses of live attenuated influenza vaccine in vaccine-naive children.
Pediatr Infect Dis J 2009; 28(5):365-71PI

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, LAIV 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 LAIV 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 LAIV was 73.5% and 57.7%, respectively, against antigenically similar strains. In year 2, absolute efficacy of a single dose of LAIV was 73.6% and 65.2%, respectively, in recipients of 2 and 1 doses of LAIV in year 1. Year 2 efficacy was 57.0% in subjects who received 2 doses of LAIV in year 1 and placebo in year 2. Safety and tolerability of LAIV were consistent with previous studies. Reactogenicity was similar between placebo groups. Seroconversion rates were significantly higher in the 2-dose versus the 1-dose LAIV group in year 1 and in both LAIV 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. LAIV excipients were not a major contributor to reactogenicity. These benefits provide support for increased use of LAIV in children > or =2 years of age.

Authors+Show Affiliations

Federal University of São Paulo, São Paulo, Brazil.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19395948

Citation

Bracco Neto, Humberto, et al. "Efficacy and Safety of 1 and 2 Doses of Live Attenuated Influenza Vaccine in Vaccine-naive Children." The Pediatric Infectious Disease Journal, vol. 28, no. 5, 2009, pp. 365-71.
Bracco Neto H, Farhat CK, Tregnaghi MW, et al. Efficacy and safety of 1 and 2 doses of live attenuated influenza vaccine in vaccine-naive children. Pediatr Infect Dis J. 2009;28(5):365-71.
Bracco Neto, H., Farhat, C. K., Tregnaghi, M. W., Madhi, S. A., Razmpour, A., Palladino, G., ... Forrest, B. D. (2009). Efficacy and safety of 1 and 2 doses of live attenuated influenza vaccine in vaccine-naive children. The Pediatric Infectious Disease Journal, 28(5), pp. 365-71. doi:10.1097/INF.0b013e31819219b8.
Bracco Neto H, et al. Efficacy and Safety of 1 and 2 Doses of Live Attenuated Influenza Vaccine in Vaccine-naive Children. Pediatr Infect Dis J. 2009;28(5):365-71. PubMed PMID: 19395948.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Efficacy and safety of 1 and 2 doses of live attenuated influenza vaccine in vaccine-naive children. AU - Bracco Neto,Humberto, AU - Farhat,Calil K, AU - Tregnaghi,Miguel Wenceslao, AU - Madhi,Shabir A, AU - Razmpour,Ahmad, AU - Palladino,Giuseppe, AU - Small,Margaret G, AU - Gruber,William C, AU - Forrest,Bruce D, AU - ,, PY - 2009/4/28/entrez PY - 2009/4/28/pubmed PY - 2009/7/8/medline SP - 365 EP - 71 JF - The Pediatric infectious disease journal JO - Pediatr. Infect. Dis. J. VL - 28 IS - 5 N2 - 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, LAIV 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 LAIV 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 LAIV was 73.5% and 57.7%, respectively, against antigenically similar strains. In year 2, absolute efficacy of a single dose of LAIV was 73.6% and 65.2%, respectively, in recipients of 2 and 1 doses of LAIV in year 1. Year 2 efficacy was 57.0% in subjects who received 2 doses of LAIV in year 1 and placebo in year 2. Safety and tolerability of LAIV were consistent with previous studies. Reactogenicity was similar between placebo groups. Seroconversion rates were significantly higher in the 2-dose versus the 1-dose LAIV group in year 1 and in both LAIV 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. LAIV excipients were not a major contributor to reactogenicity. These benefits provide support for increased use of LAIV in children > or =2 years of age. SN - 0891-3668 UR - https://www.unboundmedicine.com/medline/citation/19395948/Efficacy_and_safety_of_1_and_2_doses_of_live_attenuated_influenza_vaccine_in_vaccine_naive_children_ L2 - http://Insights.ovid.com/pubmed?pmid=19395948 DB - PRIME DP - Unbound Medicine ER -