Analysis of Viral and Host Factors on Immunogenicity of 2018, 2019, and 2020 Southern Hemisphere Seasonal Trivalent Inactivated Influenza Vaccine in Adults in Brazil

Artur Capão, Maria L. Aguiar-Oliveira, Braulia C. Caetano, Thayssa K. Neves, Paola C. Resende, Walquiria A.F. Almeida, Milene D. Miranda, Olindo A.ssis Martins-Filho, David Brown, Marilda M. Siqueira, Cristiana C. Garcia*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Annual vaccination against influenza is the best tool to prevent deaths and hospitalizations. Regular updates of trivalent inactivated influenza vaccines (TIV) are necessary due to high mutation rates in influenza viruses. TIV effectiveness is affected by antigenic mismatches, age, previous immunity, and other host factors. Studying TIV effectiveness annually in different populations is critical. The serological responses to Southern-Hemisphere TIV and circulating influenza strains were evaluated in 2018–2020 among Brazilian volunteers, using hemagglutination inhibition (HI) assays. Post-vaccination titers were corrected to account for pre-vaccination titers. Our population achieved >83% post-vaccination seroprotection levels, whereas seroconversion rates ranged from 10% to 46%. TIV significantly enhanced antibody titers and seroprotection against all prior and contemporary vaccine and circulating strains tested. Strong cross-reactive responses were detected, especially between H1N1 subtypes. A/Singapore/INFIMH-16-0019/2016, included in the 2018 TIV, induced the poorest response. Significant titer and seroprotection reductions were observed 6 and 12 months after vaccination. Age had a slight effect on TIV response, whereas previous vaccination was associated with lower seroconversion rates and titers. Despite this, TIV induced high seroprotection for all strains, in all groups. Regular TIV evaluations, based on regional influenza strain circulation, should be conducted and the factors affecting response studied.

Original languageEnglish
Article number1692
JournalViruses
Volume14
Issue number8
DOIs
Publication statusPublished - Aug 2022
Externally publishedYes

Bibliographical note

Funding Information:
We were funded by Fiocruz (POM/IOC 006.8315.089.1201; Inova COVID-19 VPPCB-005-FIO-20-2-69), CNPq (313403/2018-0 and 402457/2020–0), Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro: E-26/203.156/2017 and 26/210.196/2020, and CNPq/Ministério da Ciência, Tecnologia, Inovações e Comunicações/Ministério da Saúde (MS/FNDCT/SCTIE/Decit) (403276/2020-9).

Publisher Copyright:
© 2022 by the authors.

Keywords

  • Brazil
  • immunogenicity
  • influenza
  • seroconversion
  • seroprotection
  • vaccine

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