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An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers
Published on: December 1, 2017
Influenza A (H1N1) 2009 two-dose immunization of US children: an observer-blinded, randomized, placebo-controlled
Eric Plennevaux1, Mark Blatter, Matthew J Cornish
1Clinical Development Department, sanofi pasteur, 1541 Avenue Marcel Mérieux, 69280 Marcy l'Etoile, Lyon, France.
Insights
This pediatric study found the pandemic (H1N1) 2009 influenza vaccine is safe and effective in children. Two doses of the vaccine, regardless of hemagglutinin (HA) dose, produced strong antibody responses in children aged 6 months to 9 years.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Immunology
Background:
- Pandemic (H1N1) 2009 influenza posed a significant public health threat.
- Assessing vaccine efficacy and safety in pediatric populations is crucial for pandemic preparedness.
Purpose of the Study:
- To evaluate the safety and immunogenicity of two doses of a monovalent inactivated pandemic (H1N1) 2009 vaccine in US children.
- To compare the immune response between two different hemagglutinin (HA) doses and placebo across pediatric age groups.
Main Methods:
- A randomized, observer-blinded, US multicenter phase 2 study involving 474 children aged 6 months to 9 years.
- Participants received two doses of 7.5 μg or 15 μg HA pandemic (H1N1) 2009 vaccine or placebo, 21 days apart.
- Primary outcome measured by hemagglutination inhibition (HI) antibody responses 21 days post-vaccination; safety monitored throughout.
Main Results:
- The first vaccine dose was more immunogenic in children over 3 years old (69-75% HI titers ≥ 1:40) than in younger children (45-50%).
- A second dose significantly boosted HI antibody responses, achieving 90-99% seroprotection and seroconversion rates in both age groups.
- The vaccine demonstrated a safety and reactogenicity profile comparable to the placebo, with similar rates of local and systemic reactions.
Conclusions:
- The pandemic (H1N1) 2009 influenza vaccine is highly immunogenic in infants and children.
- The vaccine exhibits a favorable safety profile, similar to placebo, supporting its use in pediatric populations.
- Two-dose vaccination regimens effectively induce protective antibody levels against pandemic (H1N1) 2009 influenza in children.
Abstract:
The goal of this pediatric clinical trial was to assess the safety and immunogenicity of two different doses of a monovalent inactivated pandemic (H1N1) 2009 vaccine in US children aged 6 months to 9 years of age. Randomized, observer-blinded, US multicenter phase 2 study assessing 2 doses of vaccine given 21 days apart in 474 children aged 6-35 months or 3-9 years. Children in each age group were randomly assigned to receive either a pandemic (H1N1) 2009 vaccine containing 7.5 or 15 μg of hemagglutinin (HA) or placebo in a 4:4:1 ratio. Primary outcome was hemagglutination inhibition (HI) antibody responses 21 days following each vaccination. Safety was monitored throughout the study. The first dose of either A H1N1 vaccine formulation was more immunogenic in children older than 3 years than in younger children. 45-50% of children aged 6-35 months and 69-75% of children aged 3-9 year-old attained HI titers of ≥ 1:40. A second dose of A H1N1 vaccine further increased HI antibody responses with seroprotection and seroconversion rates reaching 90-99% in both age groups. Interestingly, the pandemic (H1N1) 2009 vaccine formulations elicited similar rates of solicited and unsolicited injection site and systemic reactions as the placebo. The data therefore demonstrate the high level immunogenicity in infants and children of an (H1N1) 2009 influenza vaccine displaying a safety and reactogenicity profile similar to placebo.
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