Safety and immunogenicity following administration of a live, attenuated monovalent 2009 H1N1 influenza vaccine to children and adults in two randomized controlled trials.
BACKGROUND
The safety, tolerability, and immunogenicity of a monovalent intranasal 2009 A/H1N1 live attenuated influenza vaccine (LAIV) were evaluated in children and adults.


RESULTS
Two randomized, double-blind, placebo-controlled studies were completed in children (2-17 y) and adults (18-49 y). Subjects were assigned 4:1 to receive 2 doses of H1N1 LAIV or placebo 28 days apart. The primary safety endpoint was fever ≥38.3°C during days 1-8 after the first dose; the primary immunogenicity endpoint was the proportion of subjects experiencing a postdose seroresponse. Solicited symptoms and adverse events were recorded for 14 days after each dose and safety data were collected for 180 days post-final dose. In total, 326 children (H1N1 LAIV, n = 261; placebo, n = 65) and 300 adults (H1N1 LAIV, n = 240; placebo, n = 60) were enrolled. After dose 1, fever ≥38.3°C occurred in 4 (1.5%) pediatric vaccine recipients and 1 (1.5%) placebo recipient (rate difference, 0%; 95% CI: -6.4%, 3.1%). No adults experienced fever following dose 1. Seroresponse rates in children (H1N1 LAIV vs. placebo) were 11.1% vs. 6.3% after dose 1 (rate difference, 4.8%; 95% CI: -9.6%, 13.8%) and 32.0% vs. 14.5% after dose 2 (rate difference, 17.5%; 95% CI: 5.5%, 27.1%). Seroresponse rates in adults were 6.1% vs. 0% (rate difference, 6.1%; 95% CI: -5.6%, 12.6%) and 14.9% vs. 5.6% (rate difference, 9.3%; 95% CI: -0.8%, 16.3%) after dose 1 and dose 2, respectively. Solicited symptoms after dose 1 (H1N1 LAIV vs. placebo) occurred in 37.5% vs. 32.3% of children and 41.7% vs. 31.7% of adults. Solicited symptoms occurred less frequently after dose 2 in adults and children. No vaccine-related serious adverse events occurred.


CONCLUSIONS
In subjects aged 2 to 49 years, two doses of H1N1 LAIV have a safety and immunogenicity profile similar to other previously studied and efficacious formulations of seasonal trivalent LAIV.


BACKGROUND
ClinicalTrials.gov NCT00946101, NCT00945893.
MedImmune, LLC, Gaithersburg, Maryland, United States of America. malloryr@medimmune.com
Raburn M
RM
Mallory
Elissa
E
Malkin
Christopher S
CS
Ambrose
Terramika
T
Bellamy
Li
L
Shi
Tingting
T
Yi
Taff
T
Jones
George
G
Kemble
Filip
F
Dubovsky
D000281:Administration, Intranasal; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology; D007251:Influenza, Human / Q000517:prevention & control* / Q000821:virology; D008297:Male; D008875:Middle Aged; D010919:Placebos; D055815:Young Adult
D007252:Influenza Vaccines; D010919:Placebos