| Autor: |
Capão A; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil., Aguiar-Oliveira ML; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil., Caetano BC; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil., Neves TK; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil., Resende PC; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil., Almeida WAF; Secretariat of Surveillance in Health (SVS), Ministry of Health (MoH), Brasília-Federal District, Rio de Janeiro 70723-040, Brazil., Miranda MD; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil., Martins-Filho OAS; Grupo Integrado de Pesquisas em Biomarcadores, René Rachou Institute, FIOCRUZ, Belo Horizonte 30190-002, Brazil., Brown D; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil.; UK Health Security Agency, 61 Colindale Avenue, London NW9 5EQ, UK., Siqueira MM; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil., Garcia CC; Laboratory of Respiratory Viruses and Measles, National Influenza Center (NIC)/World Health Organization (WHO), Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro 21040-900, Brazil. |
| Abstrakt: |
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. |
