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Immunogenicity of influenza vaccines administered to pregnant women in randomized clinical trials in Mali and South Africa

  • Amin, Avnika B.1
  • Nunes, Marta C.2, 3
  • Tapia, Milagritos D.4, 5
  • Madhi, Shabir A.2, 3
  • Cutland, Clare L.2, 3
  • Wairagkar, Niteen6
  • Omer, Saad B.1, 7, 8, 9
  • 1 Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, USA
  • 2 Medical Research Council: Respiratory and Meningeal Pathogens Research Unit, University of the Witwatersrand, Johannesburg, South Africa
  • 3 Department of Science and Technology—National Research Foundation, Vaccine-Preventable Diseases, Johannesburg, South Africa
  • 4 Centre pour le Développement des Vaccins, Bamako, Mali
  • 5 University of Maryland School of Medicine, Center for Vaccine Development, Baltimore, USA
  • 6 Bill & Melinda Gates Foundation, Seattle, USA
  • 7 Hubert Department of Global Health, Emory University Rollins School of Public Health, Atlanta, USA
  • 8 Emory Vaccine Center, Atlanta, USA
  • 9 Department of Pediatrics, Emory University School of Medicine, Atlanta, USA
Published Article
Elsevier Science
Publication Date
Sep 22, 2020
DOI: 10.1016/j.vaccine.2020.07.020
PMID: 32868130
PMCID: PMC7505225
PubMed Central


Background A key consideration for expanding recommendations for influenza vaccination is a robust assessment of immunogenicity and efficiency of transplacental antibody transfer after maternal vaccination. Methods We pooled data from two trials of maternal influenza vaccination to analyze vaccine immunogenicity with more power than either trial had alone. We compared hemagglutination-inhibition (HAI) titers and titer factor change for women and their infants between trial arms using t-tests; maternal and infant putative seroprotective titers (HAI ≥ 1:40) within each trial arm and maternal seroconversion between trial arms using exact tests; and transplacental antibody transfer between trial arms using t-tests. We used marginal linear models and generalized estimating equations to examine the impact of time between maternal vaccination and delivery on transplacental antibody transfer, infant titers, and infant seroprotection. Results For all vaccine components (A/H1N1, A/H3N2, and Type B), >80% of vaccinated women had seroprotective titers, >60% of them seroconverted, and >50% of their infants were born with seroprotective titers. These immunogenicity outcomes occurred more often in vaccine recipients and their infants than in controls. No difference in efficiency of transplacental antibody transfer was observed between vaccine recipients and controls. Conclusions Our results provide robust support for further expansion of maternal influenza vaccination recommendations. Clinical Trials Registration: NCT01430689 and NCT01306669.

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