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

• Type of Material: Article
• Authors: Avnika B. Amin, Emory University; Marta C. Nunes, University of Witwatersrand; Milagritos D. Tapia, University of Maryland; Shabir A. Madhi, University of Witwatersrand; Clare L. Cutland, University of Witwatersrand; Niteen Wairagkar, Bill & Melinda Gates Foundation; Saad Omer, Emory University
• Language: English
• Date: 2020-09-22
• Publisher: ELSEVIER SCI LTD
• Publication Version: Final Published Version
• Copyright Statement: © 2020 The Authors
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.vaccine.2020.07.020
• Title of Journal or Parent Work: VACCINE
• Volume: 38
• Issue: 41
• Start Page: 6478
• End Page: 6483
• Grant/Funding Information: The trials in Mali and South Africa were supported by the Bill & Melinda Gates Foundation (grant numbers OPP1002744 and OPP1002747, respectively). The pooled analysis received funding from the Bill & Melinda Gates Foundation (contract number 24090).
• Keywords: Transplacental antibody transfer; VACCINATION; Life Sciences & Biomedicine; MOTHERS; Influenza; Immunology; INFECTION; Immunogenicity; Influenza vaccine; Science & Technology; PROTECTION; Research & Experimental Medicine; Medicine, Research & Experimental; Maternal vaccination; IMMUNIZATION
• Research Categories: Biology, Virology; Health Sciences, Public Health; Health Sciences, Immunology

Abstract

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.