Antibody persistence and response to 2010–2011 trivalent influenza vaccine one year after a single dose of 2009 AS03-adjuvanted pandemic H1N1 vaccine in children

BackgroundIn 2009, several countries used the ASO3-adjuvanted pandemic A/H1N1 vaccine. We assessed the persistence of antibody and the priming induced by a single paediatric dose of this vaccine in children.MethodsChildren aged 15–120 months vaccinated one year before with the ASO3-adjuvanted monovalent pandemic vaccine were tested for the presence of antibody against 2010–2011 TIV components (A/California/7/2009(H1N1), A/Wisconsin/15/2009 (H3N2 A/Perth/16/2009-like) and B/Brisbane/60/2008) before and 21–28 days after each dose of 2010–2011 TIV. Hemagglutination-inhibition (HAI) assay was used. Children received one or two doses of 2010–2011 TIV at 21–28 days interval in relation with their previous immunization status.ResultsThe results of 128 children were included in the ATP analysis. Before the 2010–2011 TIV administration, 46% of children showed sero-protection to the A/California/7/2009(H1N1) strain (HAI titre ≥40) with lower rates of sero-protection to the H3N2A/Perth/16/2009 (37%) and B/Brisbane/60/2008 (19%). After the first dose of 2010–2011 TIV, 98%, 75%, and 57% of vaccinees attained a sero-protective titre to A/California/7/2009(H1N1), A/Perth/16/2009(H3N2), and B/Brisbane/60/2008 strain, respectively. The youngest age group showed significantly lower antibody response to the influenza B component compared to the older age groups after the first dose of vaccine. Among vaccinees who received the second dose of TIV, 96% and 87% had a sero-protective titre to H3N2A/Perth/16/2009 and B/Brisbane/60/2008, respectively. The 2010–2011 TIV was well tolerated.ConclusionsWe found substantial persistence of antibody to the A/California/7/2009 strain one year after a single paediatric dose of AS03-adjuvanted pandemic vaccine and a seroprotective level of antibody to this strain in virtually all children who received one year later a single dose of the 2010–2011 TIV. In contrast, two doses of the 2010–2011 TIV were necessary to induce an adequate immune response to the A/Perth/16/2009(H3N2) and B/Brisbane/60/2008 strains in children previously naïve to seasonal vaccine.

► pH1N1 influenza vaccine. ► Antibody persistence. ► TIV. ► Strain-specific responses.