1509. Immunogenicity of AS03-Adjuvanted H1N1 Pandemic Influenza Vaccine in HIV-Infected Children
Session: Abstracts: Oral Abstract Session: Vaccines In Children
Sunday, October 24, 2010: 8:45 AM

HIV-infected children are a high-risk group for severe influenza infection, but are known to respond poorly to influenza vaccination.  The novel AS03-adjuvanted pandemic H1N1 influenza A vaccine (Arepanrix™) became available in Canada in October 2010, but its efficacy in children with HIV is unknown.  


We prospectively assessed vaccine responses in HIV-infected children in 2 pediatric HIV clinics in Ontario, Canada.  Hemagglutination inhibition titers (HIT) were performed at baseline and 8 weeks post vaccination.  Children < 10 years of age received 2 intramuscular (IM) doses of 0.25 mL 3 weeks apart; older children received a single IM dose of 0.5 mL.  Seroprotection was defined by a HIT >/= 1:40 and seroconversion as >/= 4-fold rise in titer to >/= 1:40.


A total of 78 children were evaluated; 49% were female.  Median age, CD4 count, and viral load (VL) were 13.2 years (IQR 9.1-15.6; 33% <10 years), 659 cells/mm3 (IQR 487-1090) and < 50 copies/mL (IQR <50-1120), respectively. A total of 16 (21%) were not receiving antiretroviral therapy (ART); the remainder were on combination ART. Seroprotective HIT 8 weeks post-vaccination were demonstrated in 54 children (69%); seroconversion was observed in 33 of 76 (43%). On univariate analysis seroprotection was associated with VL (p=0.07), duration of ART (p=0.14) and baseline CD4 count (p=0.20); seroconversion was associated with VL (p=0.002), ART (p=0.025) and duration of ART (p=0.17). Regression analysis revealed VL and CD4 count to be the strongest predictors of seroprotection (p=0.009 and p=0.03, respectively); seroconversion was strongly associated with VL (p=0.003).  Mild vaccine-related side effects were seen in 85%, injection site pain being most common (65%); no serious adverse events were observed.   


HIV-infected children respond suboptimally to AS03-adjuvanted H1N1 pandemic influenza vaccine, with only 69% achieving seroprotective levels and 43% achieving seroconversion post-vaccination. VL was strongly and inversely associated with seroprotection and seroconversion.  Alternate vaccination strategies may be necessary for HIV-infected children.

Subject Category: P. Pediatric and perinatal infections

Jason C. Brophy, MD, MSc, DTM , Division of Infectious Diseases, Department of Pediatrics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
Brian Ward, MD, MSc, DTM , Infectious Diseases, McGill University, Montreal, QC, Canada
Lindy M. Samson, MD , Division of Infectious Diseases, Department of Pediatrics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
Stanley Read, MD, PhD , Division of Infectious Diseases, Department of Pediatrics, Hospital for Sick Children, Toronto, ON, Canada
Sean Ari Bitnun, MD, MSc , Division of Infectious Diseases, Department of Pediatrics, Hospital For Sick Children, Toronto, ON, Canada


J. C. Brophy, None

B. Ward, Yes
GSK: Grant Investigator,

L. M. Samson, None

S. Read, None

S. A. Bitnun, None

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