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Absence of cross-reactive antibodies to influenza A (H1N1) 2009 before and after vaccination with 2009 Southern Hemisphere seasonal trivalent influenza vaccine in children aged 6 months-9 years: a prospective study.

Abstract

BACKGROUND

Early outbreaks of the pandemic influenza A (H1N1) 2009 virus predominantly involved young children, who fuelled transmission through spread in homes and schools. Seroprevalence studies conducted on stored serum collections indicated low levels of antibody to the novel strain in this age group, leading many to recommend priority immunisation of paediatric populations.

OBJECTIVES

In a prospective study, we sought evidence of cross-reactive antibodies to the pandemic virus in children who were naïve to seasonal influenza vaccines, at baseline and following two doses of the 2009 Southern Hemisphere trivalent influenza vaccine (TIV).

PATIENTS/METHODS

Twenty children were recruited, with a median age of 4 years (interquartile range 3-5 years); all received two age appropriate doses of TIV. Paired sera were collected pre- and post-vaccination for the assessment of vaccine immunogenicity, using haemagglutination inhibition and microneutralisation assays against vaccine-related viruses and influenza A (H1N1) 2009.

RESULTS

Robust responses to H3N2 were observed regardless of age or pre-vaccination titre, with 100% seroconversion. Fewer seroconverted to the seasonal H1N1 component. Only two children were weakly seropositive (HI titre 40) to the pandemic H1N1 strain at study entry, and none showed evidence of seroconversion by HI assay following TIV administration.

CONCLUSIONS

Administration of 2009 Southern Hemisphere TIV did little to elicit cross-reactive antibodies to the pandemic H1N1 virus in children, in keeping with assay results on stored sera from studies of previous seasonal vaccines. Our findings support the recommendations for influenza A (H1N1) 2009 vaccination of children in preparation for the 2010 winter season.

Authors+Show Affiliations

Vaccine & Immunisation Research Group, Murdoch Children's Research Institute & Melbourne School of Population Health, The University of Melbourne, Parkville, Australia. j.mcvernon@unimelb.edu.auNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21138535

Citation

McVernon, Jodie, et al. "Absence of Cross-reactive Antibodies to Influenza a (H1N1) 2009 Before and After Vaccination With 2009 Southern Hemisphere Seasonal Trivalent Influenza Vaccine in Children Aged 6 Months-9 Years: a Prospective Study." Influenza and Other Respiratory Viruses, vol. 5, no. 1, 2011, pp. 7-11.
McVernon J, Laurie K, Barr I, et al. Absence of cross-reactive antibodies to influenza A (H1N1) 2009 before and after vaccination with 2009 Southern Hemisphere seasonal trivalent influenza vaccine in children aged 6 months-9 years: a prospective study. Influenza Other Respir Viruses. 2011;5(1):7-11.
McVernon, J., Laurie, K., Barr, I., Kelso, A., Skeljo, M., & Nolan, T. (2011). Absence of cross-reactive antibodies to influenza A (H1N1) 2009 before and after vaccination with 2009 Southern Hemisphere seasonal trivalent influenza vaccine in children aged 6 months-9 years: a prospective study. Influenza and Other Respiratory Viruses, 5(1), pp. 7-11. doi:10.1111/j.1750-2659.2010.00172.x.
McVernon J, et al. Absence of Cross-reactive Antibodies to Influenza a (H1N1) 2009 Before and After Vaccination With 2009 Southern Hemisphere Seasonal Trivalent Influenza Vaccine in Children Aged 6 Months-9 Years: a Prospective Study. Influenza Other Respir Viruses. 2011;5(1):7-11. PubMed PMID: 21138535.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Absence of cross-reactive antibodies to influenza A (H1N1) 2009 before and after vaccination with 2009 Southern Hemisphere seasonal trivalent influenza vaccine in children aged 6 months-9 years: a prospective study. AU - McVernon,Jodie, AU - Laurie,Karen, AU - Barr,Ian, AU - Kelso,Anne, AU - Skeljo,Maryanne, AU - Nolan,Terry, Y1 - 2010/08/24/ PY - 2010/12/9/entrez PY - 2010/12/9/pubmed PY - 2011/3/9/medline SP - 7 EP - 11 JF - Influenza and other respiratory viruses JO - Influenza Other Respir Viruses VL - 5 IS - 1 N2 - BACKGROUND: Early outbreaks of the pandemic influenza A (H1N1) 2009 virus predominantly involved young children, who fuelled transmission through spread in homes and schools. Seroprevalence studies conducted on stored serum collections indicated low levels of antibody to the novel strain in this age group, leading many to recommend priority immunisation of paediatric populations. OBJECTIVES: In a prospective study, we sought evidence of cross-reactive antibodies to the pandemic virus in children who were naïve to seasonal influenza vaccines, at baseline and following two doses of the 2009 Southern Hemisphere trivalent influenza vaccine (TIV). PATIENTS/METHODS: Twenty children were recruited, with a median age of 4 years (interquartile range 3-5 years); all received two age appropriate doses of TIV. Paired sera were collected pre- and post-vaccination for the assessment of vaccine immunogenicity, using haemagglutination inhibition and microneutralisation assays against vaccine-related viruses and influenza A (H1N1) 2009. RESULTS: Robust responses to H3N2 were observed regardless of age or pre-vaccination titre, with 100% seroconversion. Fewer seroconverted to the seasonal H1N1 component. Only two children were weakly seropositive (HI titre 40) to the pandemic H1N1 strain at study entry, and none showed evidence of seroconversion by HI assay following TIV administration. CONCLUSIONS: Administration of 2009 Southern Hemisphere TIV did little to elicit cross-reactive antibodies to the pandemic H1N1 virus in children, in keeping with assay results on stored sera from studies of previous seasonal vaccines. Our findings support the recommendations for influenza A (H1N1) 2009 vaccination of children in preparation for the 2010 winter season. SN - 1750-2659 UR - https://www.unboundmedicine.com/medline/citation/21138535/Absence_of_cross_reactive_antibodies_to_influenza_A__H1N1__2009_before_and_after_vaccination_with_2009_Southern_Hemisphere_seasonal_trivalent_influenza_vaccine_in_children_aged_6_months_9_years:_a_prospective_study_ L2 - https://doi.org/10.1111/j.1750-2659.2010.00172.x DB - PRIME DP - Unbound Medicine ER -