1456. Impact of Prior Season Influenza Vaccination on Seasonal Influenza Vaccine Effectiveness: An Analysis over Four Consecutive Seasons from the Serious Outcomes Surveillance (SOS) Network of the Canadian Immunization Research Network (CIRN)
Session: Poster Abstract Session: Influenza and Influenza Vaccines
Friday, October 6, 2017
Room: Poster Hall CD
  • Prior Vac_ID Week 2017_Final.pdf (424.3 kB)
  • Background: Recent controversy has arisen from observational studies suggesting a potential negative association between prior influenza vaccination and subsequent influenza vaccine effectiveness (VE). As immunologic theories suggest this impact could vary by season/strain, we investigated this association over 4 influenza seasons in Canada.

    Methods: The CIRN SOS Network prospectively enrolled laboratory-confirmed influenza cases and influenza-negative controls admitted to participating hospitals. Using a test-negative control design, matched conditional logistic regression modeling stratifying participants into 4 groups (not vaccinated current or prior season [referent], vaccinated prior season only, vaccinated current season only, and vaccinated both current and prior season) was used to calculate odds ratios (OR) to estimate the effect of vaccination status on influenza-related hospitalization (VE= 1-OR x100). We assessed VE overall and stratified by strain (A/H3N2, A/H1N1, and influenza B) for 4 influenza seasons in Canada: 2011/2012-2014/2015.

    Results: Although impact of prior vaccination varied, the largest strain-specific impacts were observed in the H3N2 dominant seasons 2012/2013 and 2014/2015, seasons where the H3N2 vaccine component was matched, and mismatched, respectively, to the circulating strain. In 12/13, adjusted VE against influenza H3N2 hospitalization was 58.6% (95% Confidence Interval [CI]: 32.5-74.7%) for patients vaccinated in current season only, relative to 30.9% (10.8-46.5%) among those vaccinated in both prior and current season; VE against influenza B hospitalization in 12/13 was 83.2% (18.9-96.5%) in current season only vaccinees and 54.1% (-6.0-80.2%) in both seasons vaccinees. In 14/15, H3N2 VE was 35.3% (-32.6-68.5%) in current season only vaccinees and -8.3% (-56.7-25.1%) in both seasons vaccinees.

    Conclusion: While our findings support a possible negative association between prior influenza vaccination and subsequent season VE against some strains in certain seasons, non-statistically significant reductions in VE were observed. Future prospective studies, using varying methodology to examine this association and to explore contributing biological/immunological mechanisms, are critical to inform immunization policy.

    Michaela Nichols, MSc1, Lingyun Ye, MSc1, Melissa K Andrew, MD, PhD1, Todd Hatchette, MD FRCPC2, Ardith Ambrose, RN1, Guy Boivin, MD, MSc3, William R. Bowie, MD, FRCPC, FIDSA4, Gael Dos Santos, PhD5, May Elsherif, MD1, Karen Green, MSc, RN6, Francois Haguinet, PhD5, Kevin Katz, MD, CM, MSc, FRCPC7, Jason Leblanc, PhD1, Mark Loeb, MD, MSc8, Donna Mackinnon-Cameron, MMath1, Anne Mccarthy, MD9, Janet Mcelhaney, MD, FRCPC, FACP10, Allison Mcgeer, MD, MSc6, Jeff Powis, MD, MSc, FRCPC11, David Richardson, MD12, Makeda Semret, MD13, Rohita Sharma, PhD14, Vivek Shinde, MD, MPH15, Daniel Smyth, MD, FRCPC16, Sylvie Trottier, MD, PhD3, Louis Valiquette, MD, MSc, FRCPC17, Duncan Webster, MD18 and Shelly McNeil, MD, FRCPC, FIDSA1, (1)Canadian Center for Vaccinology, IWK Health Centre and Nova Scotia Health Authority, Dalhousie University, Halifax, NS, Canada, (2)Nova Scotia Health Authority, Dalhousie University, Halifax, NS, Canada, (3)Centre Hospitalier Universitaire de Quebec, Quebec City, QC, Canada, (4)Division of Infectious Diseases, Department of Medicine, University of British Columbia, Vancouver, BC, Canada, (5)GSK, Wavre, Belgium, (6)Mount Sinai Hospital, Toronto, ON, Canada, (7)North York General Hospital, Toronto, ON, Canada, (8)McMaster University, Hamilton, ON, Canada, (9)The Ottawa Hospital, Ottawa, ON, Canada, (10)Health Sciences North Research Institute, Sudbury, ON, Canada, (11)Michael Garron Hospital, Toronto, ON, Canada, (12)William Osler Health System, Brampton, ON, Canada, (13)McGill University, Montreal, QC, Canada, (14)GSK, Mississauga, ON, Canada, (15)Novavax Vaccines, Gaithersburg, MD, (16)The Moncton Hospital, Moncton, NB, Canada, (17)Microbiology and Infectious Disease, Université de Sherbrooke, Sherbrooke, QC, Canada, (18)Saint John Regional Hospital, Dalhousie University, Saint John, NB, Canada


    M. Nichols, None

    L. Ye, None

    M. K. Andrew, GSK: Grant Investigator , Research grant
    Pfizer: Grant Investigator , Research grant
    Sanofi-Pasteur: Grant Investigator , Research grant

    T. Hatchette, GSK: Grant Investigator , Grant recipient
    Pfizer: Grant Investigator , Grant recipient
    Abbvie: Speaker for a talk on biologics and risk of TB reactivation , Speaker honorarium

    A. Ambrose, None

    G. Boivin, None

    W. R. Bowie, None

    G. Dos Santos, GSK: Employee , Salary
    Business and Decision Life Sciences (Contractor for GSK Vaccines): Independent Contractor , Salary

    M. Elsherif, Canadian Institutes of Health Research: Investigator , Research grant
    Public Health Agency of Canada: Investigator , Research grant
    GSK: Investigator , Research grant

    K. Green, None

    F. Haguinet, GSK: Employee , Salary

    K. Katz, None

    J. Leblanc, None

    M. Loeb, None

    D. Mackinnon-Cameron, None

    A. Mccarthy, None

    J. Mcelhaney, GSK: Scientific Advisor , Honorarium to institution
    Sanofi Pasteur: Scientific Advisor , Honorarium to institution

    A. Mcgeer, Hoffman La Roche: Investigator , Research grant
    GSK: Investigator , Research grant
    Sanofi Pasteur: Investigator , Research grant

    J. Powis, Merck: Grant Investigator , Research grant
    GSK: Grant Investigator , Research grant
    Roche: Grant Investigator , Research grant
    Synthetic Biologicals: Investigator , Research grant

    D. Richardson, None

    M. Semret, GSK: Investigator , Research grant
    Pfizer: Investigator , Research grant

    R. Sharma, GSK: Employee and Shareholder , Salary

    V. Shinde, Novavax: Employee , Salary
    GSK: Shareholder , Stocks
    GSK: Employee , Salary

    D. Smyth, None

    S. Trottier, Canadian Institutes of Health Research: Investigator , Research grant

    L. Valiquette, None

    D. Webster, None

    S. McNeil, GSK: Contract Clinical Trials and Grant Investigator , Research grant
    Merck: Contract Clinical Trials and Speaker's Bureau , Speaker honorarium
    Novartis: Contract Clinical Trials , No personal renumeration
    Sanofi Pasteur: Contract Clinical Trials , No personal renumeration

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 4th with the exception of research findings presented at the IDWeek press conferences.