530. Noninferior Immunologic Response of Quadrivalent, Live Attenuated Influenza Vaccine (Q/LAIV) Compared With Trivalent LAIV (T/LAIV) in Children
Session: Poster Abstract Session: Influenza Vaccines
Friday, October 21, 2011
Room: Poster Hall B1
Background: Seasonal influenza vaccines contain 3 strains, A/H1N1, A/H3N2 and B. Because B strains of 2 antigenically distinct lineages (Yamagata and Victoria) have been cocirculating, a vaccine containing 2 B strains could broaden protection against B strains.

Methods: In March 2010, 2312 US children 2–17 years old were randomized 3:1:1 (blinded) to receive Q/LAIV or one of 2 T/LAIVs containing either a B Victoria (B-V) or B Yamagata (B-Y) strain (all strains matching those of Q/LAIV). The primary objective of the study was to demonstrate the immunologic noninferiority of Q/LAIV compared with T/LAIV by comparing the post-dose strain-specific geometric mean titers (GMTs) of hemagglutination inhibition (HAI) antibodies (expressed as reciprocal dilution). Subjects 9–17 years received 1 dose of vaccine. Subjects 2–8 years received 2 doses 1 month apart. Blood was obtained 1 month after dose 1 except in seasonal influenza vaccine-naive subjects 2–8 years old, in whom it was obtained after dose 2. Solicited symptoms were collected days 0–14 after each dose, adverse events (AEs) days 0–28 after each dose and serious AEs (SAEs) days 0–180 after last dose.

Results: 

Q/LAIV was immunologically noninferior to T/LAIV, because the upper bounds of all four 95% confidence intervals (CIs) for post-dose strain-specific GMT ratios were ≤1.5, the predefined noninferiority margin.

 

Post Dose Ratio of HAI Antibody GMTs

Q/LAIV

T/LAIV

GMT Ratio (T/LAIV÷Q/LAIV)

Strain

N

GMT

N

GMT

Ratio

95% CI

A/H1N1

1327

16.7

883

17.9

1.07

0.98, 1.16

A/H3N2

1327

27.7

883

28.8

1.04

0.94, 1.14

B Yamagata

1327

49.6

445

59.8

1.21

1.07, 1.37

B Victoria

1327

35.4

437

37.0

1.05

0.93, 1.18

Data from 2 T/LAIV arms were combined for A strains.

Seroconversion rates (4-fold rise) in all subjects were comparable in both groups (Q/LAIV vs T/LAIV): 6.3% and 8.2% for A/H1N1; 3.9% and 3.6% for A/H3N2; 43.4% and 44.9% for B-Y; and 39.1% and 38.4% for B-V. Rates of solicited symptoms (SS) and AEs were comparable between Q/LAIV and T/LAIV. The largest rate difference (Q/LAIV-T/LAIV) in SS was for fever ≥38°C (1.8%). There were no related SAEs. 

Conclusion: The immunogenicity of Q/LAIV was noninferior to that of T/LAIV in children 2–17 years of age. Safety was comparable between study arms.

Sponsored by MedImmune, LLC


Subject Category: I. Adult and Pediatric Vaccines

Stan Block, MD1, Tingting Yi, PhD2 and Judith Falloon, MD2, (1)Kentucky Pediatric Research, Inc, Bardstown, KY, (2)MedImmune, Gaithersburg, MD

Disclosures:

S. Block, MedImmune: Consultant, Grant Investigator and Speaker's Bureau, Consulting fee, Research grant and Speaker honorarium

T. Yi, MedImmune: Employee, Salary

J. Falloon, MedImmune: Employee, Salary

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