Vaccination against poliomyelitis in Brazil from 2011 to 2021: successes, setbacks, and challenges ahead

Abstract The drop in childhood vaccination coverage (VC), including poliomyelitis, has become a health concern. The objective was to analyze the temporal trend of coverage of the three doses of the polio vaccine in the first 12 months of life between 2011 and 2021, in addition to mapping vaccination coverage in Brazil, including the COVID-19 pandemic period. An ecological study was carried out using interrupted time series (STI) techniques and spatial analysis, with data from the National Immunization Program Information System. The VC trend was adjusted by the Newey-West variance estimator according to the federated units and the Brazilian Deprivation Index. The VC distribution was estimated by Bayesian models and the spatial clusters by the global and local Moran index, identifying areas of lower coverage in the health regions. There was a reduction in the VC over the period in all regions, being more pronounced in the North and Northeast regions and during the Covid-19 pandemic. The biggest drops were identified in states and health regions with greater social vulnerability after 2019. The drop in VC shows that the risk of reintroduction of the wild virus is imminent and the challenges need to be faced with the strengthening of the Brazilian Health System (SUS).

摘要 包括脊髓灰质炎（poliomyelitis）在内的儿童疫苗接种率（vaccination coverage, VC）下降已成为公共健康领域的关切问题。本研究旨在分析2011至2021年间巴西婴幼儿出生后12个月内接种3剂脊髓灰质炎疫苗的时间趋势，并绘制包括新冠疫情时期在内的全国疫苗接种率空间分布图。本研究依托国家免疫规划信息系统数据，采用间断时间序列（interrupted time series, STI）分析技术与空间分析方法开展生态学研究。研究基于联邦行政单元与巴西贫困剥夺指数，采用Newey-West方差估计量对疫苗接种率趋势进行校正；通过贝叶斯模型估算疫苗接种率的空间分布，借助全局Moran指数与局部Moran指数识别空间聚类特征，进而定位出卫生辖区内接种率偏低的区域。研究期内所有区域的疫苗接种率均出现下降，其中北部与东北部地区以及新冠疫情期间的下降幅度更为显著。2019年后，社会脆弱性更高的州与卫生辖区出现了最大幅度的接种率下滑。疫苗接种率的下降表明野生脊髓灰质炎病毒再次传入的风险迫在眉睫，需通过强化巴西卫生系统（SUS）来应对这些挑战。