525. Persistence of Neutralizing Antibodies Following Two Doses of an AS03-adjuvanted Pandemic H1N1 Influenza Vaccine in Children Aged 6 months–17 years
Session: Poster Abstract Session: Influenza Vaccines
Friday, October 21, 2011
Room: Poster Hall B1
Background: To assess persistence of the immune response to two doses of an AS03-adjuvanted pandemic H1N1 split-virus influenza vaccine in children.

Methods: Healthy children were enrolled in a randomized (6–35 months), or non-randomized (3–17 years) open-label study. Two doses (21 days apart) of an AS03-adjuvanted A/California/7/2009 (H1N1) influenza vaccine were given, containing 1.9 μg of hemagglutinin antigen (HA) and AS03B (6–35 months, N=104) or 3.75 μg of HA and AS03A (6–35 months, N=53 [data not shown]: 3–17 years, N=202 [immunogenicity analyses performed on 2 age strata: 3–8 years; 9–17 years]). Geometric mean titers (GMTs) of serum neutralizing antibodies to A/Netherlands/602/09 H1N1 were assessed on Day 0 (D0), Day 21 (D21), Day 42 (D42) and approximately 1 year (M11–12) after vaccination; vaccine response rates (VRRs) were assessed on D21, D42 and M11–12. Safety including medically attended adverse events (MAEs), AEs of special interest (AESIs), potential immune-mediated diseases (pIMDs) and serious AEs (SAEs) was assessed up to M12.

Results: 57 children aged 6–35 months, and 90 children aged 3–17 years were included in the neutralizing antibody immunogenicity cohorts. At M11–12 all subjects were still seropositive for neutralizing antibodies (≥8 1/DIL).

 

 

GMT (95% CI)

VRR % (95% CI)

635 months

D0 (n=57)

D21 (n=53)

D42 (n=54)

M11–12 (n=49)

5.6 (3.9–7.9)

36.9 (24.5–55.4)

1416.1 (1048.1–1913.3)

312.8 (223.1–438.6)

54.7 (40.4–68.4)

98.1 (90.1–100)

91.8 (80.4–97.7)

38 years

D0 (n=52)

D21 (n=52)

D42 (n=49)

M11–12 (n=47)

4.3 (3.8–4.9)

86.7 (63.0–119.3)

991.0 (754.4–1301.7)

210.8 (167.2–265.8)

86.0 (75.3–94.2)

100 (92.5–100)

100 (92.1–100)

917 years

D0 (n=38)

D21 (n=38)

D42 (n=38)

M11–12 (n=38)

6.6 (4.3–10.2)

161.1 (90.5–286.7)

692.2 (460.6–1040.1)

133.7 (97.8–182.8)

86.8 (71.9–95.6)

100 (90.7–100)

89.5 (75.2–97.1)

Three children reported SAEs which were considered by the investigator to be unrelated to vaccination. No subjects withdrew from the study due to an AE or SAE.

Conclusion: Two doses, adjusted by age, of the AS03-adjuvanted H1N1 vaccine elicited a persistent immune response up to M11–12 in all age strata, with a clinically acceptable safety profile.


Subject Category: I. Adult and Pediatric Vaccines

Alfonso Carmona1, Juan Carlos Tejedor2, Jose Manuel Merino3, Javier Aristegui4, Jose Garcia-Sicilia5, Felix Omenaca5, Vinod Bambure6, Karl Walravens7 and Ilse Dieussaert8, (1)Instituto Hispalense de Pediatría, Sevilla, Spain, Sevilla, Spain, (2)Hosp. de Móstoles, Móstoles (Madrid), Spain, (3)Hospital General Yagüe, Burgos, Spain, (4)Basurto Hospital, Bilbao, Spain, Bilbao, Spain, (5)La Paz Hospital, Madrid, Spain, Madrid, Spain, (6)6Clinical Development Operations Center, GlaxoSmithKline – Bangalore, India, Karnataka, India, (7)7Research and Development, GlaxoSmithKline Biologicals, Rixensart, Belgium, Wavre, Belgium, (8)GlaxoSmithKline Biologicals, Wavre, Belgium, Wavre, Belgium

Disclosures:

A. Carmona, GSK: Investigator, investigator fees and travel expenses

J. C. Tejedor, None

J. M. Merino, GSK: Consultant, Investigator, Scientific Advisor and Speaker's Bureau, Consulting fee, Research support and Speaker honorarium

J. Aristegui, None

J. Garcia-Sicilia, GlaxoSmithKline: Investigator, Money to my institution (Fundacion Investigacion Biomedica. Hospital Universitario La Paz)

F. Omenaca, GSK Biologicals: Investigator, Research support and Speaker honorarium

V. Bambure, GlaxoSmithKline: Employee, Salary

K. Walravens, GSK: Employee, Salary

I. Dieussaert, GSK: Employee, Salary

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