Program Schedule

Factors Associated with Influenza A (H1N1)pdm09 (pH1N1) Vaccine Failure among Children Aged 5-17 Years

Session: Poster Abstract Session: Vaccines: Influenza
Friday, October 10, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
  • Option C_IDSA_vaccinefailure.pdf (168.8 kB)
  • Background: Immunologic factors associated with influenza vaccine failure in children are not well understood. In 2013-14, we prospectively followed a cohort of vaccinated children 5-17 years old and examined factors associated with pH1N1 infection. 

    Methods: We recruited children who were enrolled in a study of influenza vaccine effectiveness during the prior 2012-13 season; all had medically attended acute respiratory illness, were tested for influenza, and had known vaccination history. Participants received one dose of 2013-14 vaccine, either inactivated influenza vaccine (IIV3) or quadrivalent live attenuated influenza vaccine (LAIV4), based on preference. Hemagglutination-inhibition (HI) titers against pH1N1 were measured pre- and 21 days post-vaccination. Seroprotection was defined as HI titer ≥1:40. Children <9 years were classified as partially vaccinated if they had received no prior dose of a vaccine containing pH1N1. Active surveillance was performed for acute respiratory illness; nasal and throat swabs from ill children were tested by RT-PCR. Cases were children with pH1N1 infection (vaccine failures); all other children served as controls. Logistic regression was used to assess factors associated with vaccine failure.

    Results: During 2013-14, among 162 vaccinated children, 11 (7%) were pH1N1 cases. Eight (73%) cases and 54 (36%) controls had received 2013-14 LAIV4 (p=0.02). Postvaccination HI titers against pH1N1 were <1:40 in 10 (91%) cases and 34 (23%) controls (p<0.001).  Compared to children 9-17 years, risk of vaccine failure was higher in children 5-8 years with no prior pH1N1 vaccination (OR 74; 95% CI 7.7, 720), and in children 5-8 years with ≥1 prior pH1N1 vaccinations (OR 5.9; 95% CI 1.2, 31). There were no differences between vaccine failures and controls by sex, high risk condition, history of influenza infection in 2012-13, or age at first influenza vaccination.

    Conclusion: Vaccine failure in children was associated with receipt of LAIV4, low postvaccination HI titer, and younger age. The risk was highest among children 5-8 years old who had not been previously vaccinated. Larger studies in children are needed to better understand risk of vaccine failure.

    Huong Mclean, PhD, MPH1, Jennifer King, MPH2, Maria Sundaram, MSPH2, Jennifer Meece, PhD3, Sarah Spencer, Ph.D.4, Jin Hyang Kim, PhD4, Thomas Friedrich, PhD5, Brendan Flannery, PhD4, Alicia M. Fry, MD, MPH4 and Edward Belongia, MD2, (1)Marshfield Clinic Research Foundation, Marshfield, WI, (2)Center for Clinical Epidemiology and Population Health, Marshfield Clinic Research Foundation, Marshfield, WI, (3)Integrated Research and Diagnositic Laboratory, Marshfield Clinic Research Foundation, Marshfield, WI, (4)Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, (5)Pathobiological Sciences, University of Wisconsin School of Veterinary Medicine, Madison, WI


    H. Mclean, MedImmune: Collaborator, Research grant

    J. King, None

    M. Sundaram, MedImmune, LLC: Project scientist on MedImmune-funded grant, Research grant

    J. Meece, None

    S. Spencer, None

    J. H. Kim, None

    T. Friedrich, None

    B. Flannery, None

    A. M. Fry, None

    E. Belongia, Medimmune LLC: Grant Investigator, Grant recipient

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