Clinical and immune responses to inactivated influenza A(H1N1)pdm09 vaccine in children

Karen L. Kotloff, Natasha B. Halasa, Christopher J. Harrison, Janet A. Englund, Emmanuel B. Walter, James C. King, C. Buddy Creech, Sara A. Healy, Rowena J. Dolor, Ina Stephens, Kathryn M. Edwards, Diana L. Noah, Heather Hill, Mark Wolff

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Background: As the influenza A H1N1 pandemic emerged in 2009, children were found to experience high morbidity and mortality and were prioritized for vaccination. This multicenter, randomized, double-blind, age-stratified trial assessed the safety and immunogenicity of inactivated influenza A(H1N1)pdm09 vaccine in healthy children aged 6 months to 17 years. Methods: Children received 2 doses of approximately 15 or 30 μg hemagglutin antigen 21 days apart. Reactogenicity was assessed for 8 days after each dose, adverse events through day 42, and serious adverse events or new-onset chronic illnesses through day 201. Serum hemagglutination inhibition titers were measured on days 0 (prevaccination), 8, 21, 29 and 42. Results: A total of 583 children received the first dose and 571 received the second dose of vaccine. Vaccinations were generally well-tolerated and no related serious adverse events were observed. The 15 μg dosage elicited a seroprotective hemagglutination inhibition (≥1:40) in 20%, 47% and 93% of children in the 6-35 month, 3-9 year and 10-17 year age strata 21 days after dose 1 and in 78%, 82% and 98% of children 21 days after dose 2, respectively. The 30 μg vaccine dosage induced similar responses. Conclusions: The inactivated influenza A(H1N1)pdm09 vaccine exhibited a favorable safety profile at both dosage levels. While a single 15 or 30 μg dose induced seroprotective antibody responses in most children 10-17 years of age, younger children required 2 doses, even when receiving dosages 4- to 6-fold higher than recommended. Well-tolerated vaccines are needed that induce immunity after a single dose for use in young children during influenza pandemics.

Original languageEnglish (US)
Pages (from-to)865-871
Number of pages7
JournalPediatric Infectious Disease Journal
Issue number8
StatePublished - Aug 2014
Externally publishedYes


  • Adverse effects
  • Children
  • Inactivated vaccines
  • Infants
  • Influenza vaccines/immunology
  • Pandemic
  • Phase II
  • Randomized trial

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Microbiology (medical)
  • Infectious Diseases


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