545.   Immunogenicity of a Heterologous H5N1 Influenza Booster Vaccine 6 or 18 Months after Primary Vaccination in Adults
Session: Poster Abstract Session: Influenza Vaccines
Friday, October 21, 2011
Room: Poster Hall B1
Background: 

One of the influenza pandemic preparedness strategies involves priming a population with a pre-pandemic subtype-specific vaccine, followed by boosting with a strain-matched vaccine during the pandemic.

Methods: 

In this phase II, observer-blind, multicenter trial, 841 adults aged ≥18 years were randomized to 7 groups to receive a single priming dose with a subclade 2.1 A/Indonesia/5/2005 (H5N1) vaccine (3.75 μg or 7.5 μg hemagglutinin antigen [HA]) or placebo (P) at Day 0 (D0), followed 6 or 18 months later (M6 or M18) with a subclade 2.2 (A/turkey/Turkey/1/05) H5N1 booster vaccine or P (table). Vaccines were adjuvanted with AS03A or AS03B (α-tocopherol/squalene o/w emulsion [11.9 mg or 5.9 mg tocopherol, respectively]). A/turkey/Turkey/1/05 HI antibodies were measured before administration, and at 10 and 42 days after the priming and booster vaccinations. Solicited and unsolicited adverse events (AEs) were collected for 7 and 42 days, respectively, after each dose. Serious AEs (SAEs) were collected during the reported study period (D0 to M18).

Results: 

10 days after the M18 injection, the lower limit of the 97.5% confidence interval  for the difference in seroconversion rates (SCRs) and adjusted geometric mean antibody titer (GMT) ratios between primed (A–F) and H5N1-naïve subjects (G) was >15% and >2.0, respectively (primary endpoint based on hemagglutination inhibition antibody). SCRs/GMTs were higher in primed subjects, compared with H5N1-naïve subjects for subjects boosted at M6 and M18 (Table). There were no differences between groups in terms of solicited or unsolicited AEs or SAEs.

Group

Schedule

Immune response for A/Turkey 10 days after booster

D0

(A/Indonesia or P)

Booster (A/Turkey or P)

SCR

GMT

M6

M18

A

3.75 µg AS03B

3.75 µg AS03B

P

77.7

308.4

B

7.5 µg AS03B

7.5 µg AS03B

P

94.2

374.4

C

3.75 µg AS03A

P

3.75 µg AS03A

85.5

356.7

D

3.75 µg AS03B

P

3.75 µg AS03B

93.1

266.4

E

7.5 µg AS03A

P

7.5 µg AS03A

91.3

446.6

F

7.5 µg AS03B

P

7.5 µg AS03B

90.3

343.9

G

P

3.75 µg AS03A

3.75 µg AS03A

44.4

43.5

Conclusion: 

All adjuvant and antigen combinations tested conferred significant priming, and H5N1-subtype specific priming persisted for 18 months. All vaccines were found to have clinically acceptable safety profiles.


Subject Category: I. Adult and Pediatric Vaccines

Joanne Langley, MD, Canadian Center for Vaccinology, Dalhousie University IWK Health Centre and Capital Health, Halifax, NS, Canada, Louise Frenette, MD, QT Research, Sherbrooke, QC, Canada, Robert Jeanfreau, MD, Jeanfreau and Jeanfreau Mds, Metairie, LA, Laurence Chu, MD, Benchmark Research, Austin, TX, Shelly McNeil, MD, Dalhousie University, Canadian Center for Vaccinology, IWK Health Centre, Halifax, NS, Canada, Scott Halperin, MD, Dalhousie University, Canadian Center for Vaccinology, IWK Health Centre and Capital Health, Halifax, NS, Canada, Mamadou Dramé, PhD, GlaxoSmithKline, King of Prussia, PA, Louis Fries, GlaxoSmithKline Biologicals, Columbia, MD and David Vaughn, GlaxoSmithKline Biologicals, King of Prussia, PA

Disclosures:

J. Langley, GSK Biologicals: Investigator, Research grant

L. Frenette, None

R. Jeanfreau, None

L. Chu, None

S. McNeil, GSK : Grant Investigator, Research grant

S. Halperin, GSK: Investigator, Research support

M. Dramé, GSK: Employee, Salary

L. Fries, GSK: Employee, Salary

D. Vaughn, GSK: Employee, Salary

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