Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number.
Background Yellow fever is endemic in Africa and the Americas, occurring in urban or sylvatic environments. The infection presents varying symptoms, with high case-fatality among severe cases. In 2016, Brazil had sylvatic yellow fever outbreaks with more than 11 thousand cases, predominantly affecti...
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ftdoajarticles:oai:doaj.org/article:f2598ffd62b9440fb3a49c259646f7a8 2023-05-15T15:16:20+02:00 Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number. Fernanda Cristina da Silva Lopes Ferreira Luiz Antônio Bastos Camacho Daniel Antunes Maciel Villela 2022-09-01T00:00:00Z https://doi.org/10.1371/journal.pntd.0010741 https://doaj.org/article/f2598ffd62b9440fb3a49c259646f7a8 EN eng Public Library of Science (PLoS) https://doi.org/10.1371/journal.pntd.0010741 https://doaj.org/toc/1935-2727 https://doaj.org/toc/1935-2735 1935-2727 1935-2735 doi:10.1371/journal.pntd.0010741 https://doaj.org/article/f2598ffd62b9440fb3a49c259646f7a8 PLoS Neglected Tropical Diseases, Vol 16, Iss 9, p e0010741 (2022) Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 article 2022 ftdoajarticles https://doi.org/10.1371/journal.pntd.0010741 2022-12-30T19:53:02Z Background Yellow fever is endemic in Africa and the Americas, occurring in urban or sylvatic environments. The infection presents varying symptoms, with high case-fatality among severe cases. In 2016, Brazil had sylvatic yellow fever outbreaks with more than 11 thousand cases, predominantly affecting the country's Southeast region. The state of Minas Gerais accounted for 30% of cases, even after the vaccine had been included in the immunization calendar for at least 30 years. Methodology and principal findings We applied parameters described in the literature from yellow fever disease into a compartmental model of vector-borne diseases, using namely generation time intervals, vital host and vector parameters, and force of infection, using macroregions as the spatial unit and epidemiological weeks as the time interval. The model permits obtaining the reproduction number, which we analyzed from reported cases of yellow fever from 2016 to 2018 in residents of the state of Minas Gerais, Brazil. Minas Gerais recorded two outbreak periods, starting in EW 51/2016 and EW 51/2017. Of all the reported cases (3,304), 57% were men 30 to 59 years of age. Approximately 27% of cases (905) were confirmed, and 22% (202) of these individuals died. The estimated effective reproduction number varied from 2.7 (95% CI: 2.0-3.6) to 7.2 (95% CI: 4.4-10.9], found in the Oeste and Nordeste regions, respectively. Vaccination coverage in children under one year of age showed heterogeneity among the municipalities comprising the macroregions. Conclusion The outbreaks in multiple parts of the state and the estimated Re values raise concern since the state population was partially vaccinated. Heterogeneity in vaccination coverage may have been associated with the occurrence of outbreaks in the first period, while the subsequent intense vaccination campaign may have determined lower Re values in the second period. Article in Journal/Newspaper Arctic Directory of Open Access Journals: DOAJ Articles Arctic Nordeste ENVELOPE(-66.867,-66.867,-68.167,-68.167) PLOS Neglected Tropical Diseases 16 9 e0010741 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 |
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Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 Fernanda Cristina da Silva Lopes Ferreira Luiz Antônio Bastos Camacho Daniel Antunes Maciel Villela Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number. |
topic_facet |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 |
description |
Background Yellow fever is endemic in Africa and the Americas, occurring in urban or sylvatic environments. The infection presents varying symptoms, with high case-fatality among severe cases. In 2016, Brazil had sylvatic yellow fever outbreaks with more than 11 thousand cases, predominantly affecting the country's Southeast region. The state of Minas Gerais accounted for 30% of cases, even after the vaccine had been included in the immunization calendar for at least 30 years. Methodology and principal findings We applied parameters described in the literature from yellow fever disease into a compartmental model of vector-borne diseases, using namely generation time intervals, vital host and vector parameters, and force of infection, using macroregions as the spatial unit and epidemiological weeks as the time interval. The model permits obtaining the reproduction number, which we analyzed from reported cases of yellow fever from 2016 to 2018 in residents of the state of Minas Gerais, Brazil. Minas Gerais recorded two outbreak periods, starting in EW 51/2016 and EW 51/2017. Of all the reported cases (3,304), 57% were men 30 to 59 years of age. Approximately 27% of cases (905) were confirmed, and 22% (202) of these individuals died. The estimated effective reproduction number varied from 2.7 (95% CI: 2.0-3.6) to 7.2 (95% CI: 4.4-10.9], found in the Oeste and Nordeste regions, respectively. Vaccination coverage in children under one year of age showed heterogeneity among the municipalities comprising the macroregions. Conclusion The outbreaks in multiple parts of the state and the estimated Re values raise concern since the state population was partially vaccinated. Heterogeneity in vaccination coverage may have been associated with the occurrence of outbreaks in the first period, while the subsequent intense vaccination campaign may have determined lower Re values in the second period. |
format |
Article in Journal/Newspaper |
author |
Fernanda Cristina da Silva Lopes Ferreira Luiz Antônio Bastos Camacho Daniel Antunes Maciel Villela |
author_facet |
Fernanda Cristina da Silva Lopes Ferreira Luiz Antônio Bastos Camacho Daniel Antunes Maciel Villela |
author_sort |
Fernanda Cristina da Silva Lopes Ferreira |
title |
Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number. |
title_short |
Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number. |
title_full |
Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number. |
title_fullStr |
Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number. |
title_full_unstemmed |
Occurrence of yellow fever outbreaks in a partially vaccinated population: An analysis of the effective reproduction number. |
title_sort |
occurrence of yellow fever outbreaks in a partially vaccinated population: an analysis of the effective reproduction number. |
publisher |
Public Library of Science (PLoS) |
publishDate |
2022 |
url |
https://doi.org/10.1371/journal.pntd.0010741 https://doaj.org/article/f2598ffd62b9440fb3a49c259646f7a8 |
long_lat |
ENVELOPE(-66.867,-66.867,-68.167,-68.167) |
geographic |
Arctic Nordeste |
geographic_facet |
Arctic Nordeste |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
PLoS Neglected Tropical Diseases, Vol 16, Iss 9, p e0010741 (2022) |
op_relation |
https://doi.org/10.1371/journal.pntd.0010741 https://doaj.org/toc/1935-2727 https://doaj.org/toc/1935-2735 1935-2727 1935-2735 doi:10.1371/journal.pntd.0010741 https://doaj.org/article/f2598ffd62b9440fb3a49c259646f7a8 |
op_doi |
https://doi.org/10.1371/journal.pntd.0010741 |
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PLOS Neglected Tropical Diseases |
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16 |
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9 |
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e0010741 |
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