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. 2023 Aug 28:26:e230037.
doi: 10.1590/1980-549720230037. eCollection 2023.

Temporal and spatial distribution of polio vaccine coverage in Brazil between 1997 and 2021

[Article in English, Portuguese]
Nathanael de Souza Maciel  1 , Hévila Medeiros Ferreira Gomes Braga  2 , Francisca Jessika Nunes de Moura  1 , Francisco Jardsom Moura Luzia  2 , Isabelle E Silva Sousa  2 , Emilia Soares Chaves Rouberte  2
Affiliations

Temporal and spatial distribution of polio vaccine coverage in Brazil between 1997 and 2021

[Article in English, Portuguese]
Nathanael de Souza Maciel et al. Rev Bras Epidemiol. .

Erratum in

  • ERRATUM.
    [No authors listed] [No authors listed] Rev Bras Epidemiol. 2023 Oct 27;26:e20230037erratum.1. doi: 10.1590/1980-549720230037erratum.1. Rev Bras Epidemiol. 2023. PMID: 37909631 Free PMC article.

Abstract
in English, Portuguese

Objective: To analyze the temporal and spatial distribution of polio vaccine coverage in Brazilian states.

Methods: An ecological time series study was conducted using data from the National Immunization Program Information System. The analyzed period was from 1997 to 2021. Joinpoint software was used to calculate the annual percentage change and average annual percentage change through regressions. QGIS 3.10.7 software was used to construct thematic maps. GeoDa 1.20.0.10 software was used to estimate spatial autocorrelation using the Global Moran's Index and Local Moran's Index.

Results: National vaccine coverage in 1997 was 89.27%, decreasing to 61.32% in 2021. The trend analysis indicated an average annual decrease of 1.5% in polio vaccine coverage in Brazil. Across the country, 17 states showed a statistically significant reduction in the average annual percentage change rate. The highest average reduction rates in vaccine coverage among Brazilian states were observed in Amapá (-3.7%; 95%CI -6.0; -1.4) and Pernambuco (-3.3%; 95%CI -4.0; -2.5). In the spatial analysis, in Moran Global, a positive autocorrelation was identified in the years 2012 to 2021 (p<0.02), with an index value of 0.361, which means that geographically close areas tended to have similar levels of vaccination coverage.

Conclusion: There was significant heterogeneity in coverage among states and a strong decrease trend in vaccination rates, which could facilitate the circulation of the poliovirus and pose a threat to the susceptible population.

Objetivo:: Analisar a distribuição temporal e espacial da cobertura da vacina contra poliomielite nos estados brasileiros.

Métodos:: Estudo ecológico de séries temporais, cuja fonte de dados foi o Sistema de Informação do Programa Nacional de Imunizações. O período analisado foi de 1997 a 2021. Utilizou-se o software Joinpoint para calcular a variação percentual anual e variação percentual anual média por meio de regressões. Para construção de mapas temáticos foi utilizado o software QGis 3.10.7. Para estimar a autocorrelação espacial com o Índice de Moran Global e Índice de Moran Local foi utilizado o software GeoDa 1.20.0.10.

Resultados:: A cobertura vacinal nacional em 1997 foi de 89,27%, passando para 61,32% em 2021. A análise de tendência apontou o decréscimo médio de 1,5% ao ano na cobertura da vacina contra poliomielite no Brasil. Em todo o país, 17 estados apresentaram redução estatisticamente significativa na taxa de variação percentual anual média. As maiores taxas médias de redução da cobertura vacinal entre os estados brasileiros foram observadas no Amapá (−3,7%; IC95% −6,0; −1,4) e em Pernambuco (−3,3%; IC95% −4,0; −2,5). Na análise espacial, no Moran Global, foi identificada autocorrelação positiva nos anos de 2012 a 2021 (p<0,02), com valor de índice de 0,361, o que significa que as áreas geograficamente próximas tenderam a ter níveis semelhantes de cobertura vacinal.

Conclusão:: Evidenciou-se expressiva heterogeneidade na cobertura entre os estados e forte tendência de queda dos índices, o que pode propiciar a circulação do poliovírus e colocar sob ameaça a população susceptível.

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Conflict of interest statement

CONFLICT OF INTERESTS: nothing to declare

Figures

Figure 1
Figure 1. Polio vaccine coverage, according to Brazilian regions. Brazil, 1997–2021.
Figure 2
Figure 2. Temporal and spatial distribution of polio vaccine coverage, according to states. Brazil, 1997 to 2005, 2006 to 2013, 2014 to 2021, and 1997 to 2021.
See this image and copyright information in PMC

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