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Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil
PURPOSE: In the elderly population, the influenza infection and its clinical complications are important causes of hospitalization and death, particularly, in longer-lived age. The objective of this study is to analyze the impact of influenza virus circulation on mortality in the elderly and adults,...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Frontiers Media S.A.
2018
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5767013/ https://www.ncbi.nlm.nih.gov/pubmed/29375560 http://dx.doi.org/10.3389/fimmu.2017.01903 |
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author | Freitas, André Ricardo Ribas Donalisio, Maria Rita |
author_facet | Freitas, André Ricardo Ribas Donalisio, Maria Rita |
author_sort | Freitas, André Ricardo Ribas |
collection | PubMed |
description | PURPOSE: In the elderly population, the influenza infection and its clinical complications are important causes of hospitalization and death, particularly, in longer-lived age. The objective of this study is to analyze the impact of influenza virus circulation on mortality in the elderly and adults, in years with different predominant virus strains. METHODS: We performed a time trend study to evaluated excess of mortality for pneumonia and influenza, respiratory disease, and all-causes in southern region of Brazil, from 2002 to 2015. After considering other models, we opted for Serfling regression. Excess of death rates per 100,000 inhabitants were analyzed in specific age groups (24–59, 60–69, 70–79, ≥80 years) and by year of occurrence. Mortality information were taken from Brazilian Mortality Information System and etiological data were accessed in Sentinel Virological Surveillance database, getting the weekly positivity of the immunofluorescence tests for influenza A (H1N1, H3N2), and B. RESULTS: In southern Brazil, there is an evident seasonal pattern of all death outcomes among different age groups in the dry and cold season (April–September). The highest excess mortality rates occurs among older, particularly in years of circulation of influenza AH3N2, especially among people ≥80 years, in 2003 and 2007—years of great severity of influenza activity. After 2009, with the introduction of the pandemic influenza AH1N1, we observed a lower impact on the mortality of the elderly compared to <60 years. DISCUSSION: A cross reactivity antibody response from past exposure probably provided protection against disease in the elderly. Despite not controlling for comorbidities, climate, and vaccination, for the >70 years, ratio of respiratory diseases excess mortality rates between AH1N1 (2009) and severe year of H3N2 (2007) shows protection in the pandemic year and great vulnerability during AH3N2 virus predominance. CONCLUSION: The reduced immune response to infection, and to vaccination, and presence of comorbidities recommend a special attention to this age group in Brazil. Besides medical assistance, the timeliness of vaccine campaigns, its composition, and etiological surveillance of respiratory diseases are some of the preventive and public health measures. |
format | Online Article Text |
id | pubmed-5767013 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-57670132018-01-26 Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil Freitas, André Ricardo Ribas Donalisio, Maria Rita Front Immunol Immunology PURPOSE: In the elderly population, the influenza infection and its clinical complications are important causes of hospitalization and death, particularly, in longer-lived age. The objective of this study is to analyze the impact of influenza virus circulation on mortality in the elderly and adults, in years with different predominant virus strains. METHODS: We performed a time trend study to evaluated excess of mortality for pneumonia and influenza, respiratory disease, and all-causes in southern region of Brazil, from 2002 to 2015. After considering other models, we opted for Serfling regression. Excess of death rates per 100,000 inhabitants were analyzed in specific age groups (24–59, 60–69, 70–79, ≥80 years) and by year of occurrence. Mortality information were taken from Brazilian Mortality Information System and etiological data were accessed in Sentinel Virological Surveillance database, getting the weekly positivity of the immunofluorescence tests for influenza A (H1N1, H3N2), and B. RESULTS: In southern Brazil, there is an evident seasonal pattern of all death outcomes among different age groups in the dry and cold season (April–September). The highest excess mortality rates occurs among older, particularly in years of circulation of influenza AH3N2, especially among people ≥80 years, in 2003 and 2007—years of great severity of influenza activity. After 2009, with the introduction of the pandemic influenza AH1N1, we observed a lower impact on the mortality of the elderly compared to <60 years. DISCUSSION: A cross reactivity antibody response from past exposure probably provided protection against disease in the elderly. Despite not controlling for comorbidities, climate, and vaccination, for the >70 years, ratio of respiratory diseases excess mortality rates between AH1N1 (2009) and severe year of H3N2 (2007) shows protection in the pandemic year and great vulnerability during AH3N2 virus predominance. CONCLUSION: The reduced immune response to infection, and to vaccination, and presence of comorbidities recommend a special attention to this age group in Brazil. Besides medical assistance, the timeliness of vaccine campaigns, its composition, and etiological surveillance of respiratory diseases are some of the preventive and public health measures. Frontiers Media S.A. 2018-01-08 /pmc/articles/PMC5767013/ /pubmed/29375560 http://dx.doi.org/10.3389/fimmu.2017.01903 Text en Copyright © 2018 Freitas and Donalisio. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Immunology Freitas, André Ricardo Ribas Donalisio, Maria Rita Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil |
title | Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil |
title_full | Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil |
title_fullStr | Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil |
title_full_unstemmed | Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil |
title_short | Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil |
title_sort | excess of mortality in adults and elderly and circulation of subtypes of influenza virus in southern brazil |
topic | Immunology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5767013/ https://www.ncbi.nlm.nih.gov/pubmed/29375560 http://dx.doi.org/10.3389/fimmu.2017.01903 |
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