Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America.
Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
PLoS Med. 2022 Sep 8;19(9):e1004093. doi: 10.1371/journal.pmed.1004093. eCollection 2022 Sep.
The structural environment of urban slums, including physical, demographic, and socioeconomic attributes, renders inhabitants more vulnerable to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Yet, little is known about the specific determinants that contribute to high transmission within these communities. We therefore aimed to investigate SARS-CoV-2 seroprevalence in an urban slum in Brazil.
We performed a cross-sectional serosurvey of an established cohort of 2,041 urban slum residents from the city of Salvador, Brazil between November 2020 and February 2021, following the first Coronavirus Disease 2019 (COVID-19) pandemic wave in the country and during the onset of the second wave. The median age in this population was 29 years (interquartile range [IQR] 16 to 44); most participants reported their ethnicity as Black (51.5%) or Brown (41.7%), and 58.5% were female. The median size of participating households was 3 (IQR 2 to 4), with a median daily per capita income of 2.32 (IQR 0.33-5.15) US Dollars. The main outcome measure was presence of IgG against the SARS-CoV-2 spike protein. We implemented multilevel models with random intercepts for each household to estimate seroprevalence and associated risk factors, adjusting for the sensitivity and specificity of the assay, and the age and gender distribution of our study population. We identified high seroprevalence (47.9%, 95% confidence interval [CI] 44.2% to 52.1%), particularly among female residents (50.3% [95% CI 46.3% to 54.8%] versus 44.6% [95% CI 40.1% to 49.4%] among male residents, p < 0.01) and among children (54.4% [95% CI 49.6% to 59.3%] versus 45.4% [95% CI 41.5% to 49.7%] among adults, p < 0.01). Adults residing in households with children were more likely to be seropositive (48.6% [95% CI 44.8% to 52.3%] versus 40.7% [95% CI 37.2% to 44.3%], p < 0.01). Women who were unemployed and living below the poverty threshold (daily per capita household income <$1.25) were more likely to be seropositive compared to men with the same employment and income status (53.9% [95% CI 47.0% to 60.6%] versus 32.9% [95% CI 23.2% to 44.3%], p < 0.01). Participation in the study was voluntary, which may limit the generalizability of our findings.
Prior to the peak of the second wave of the COVID-19 pandemic, cumulative incidence as assessed by serology approached 50% in a Brazilian urban slum population. In contrast to observations from industrialized countries, SARS-CoV-2 incidence was highest among children, as well as women living in extreme poverty. These findings emphasize the need for targeted interventions that provide safe environments for children and mitigate the structural risks posed by crowding and poverty for the most vulnerable residents of urban slum communities.
城市贫民窟的结构环境，包括物理、人口和社会经济属性，使居民更容易感染严重急性呼吸综合征冠状病毒 2 型（SARS-CoV-2）。然而，对于导致这些社区内高传播的具体决定因素，人们知之甚少。因此，我们旨在调查巴西一个城市贫民窟的 SARS-CoV-2 血清阳性率。
我们对巴西萨尔瓦多市的一个已建立的城市贫民窟居民队列进行了横断面血清学调查，该队列有 2041 名居民，调查时间为 2020 年 11 月至 2021 年 2 月，正值该国第一波冠状病毒病 2019（COVID-19）大流行和第二波大流行开始之际。该人群的中位年龄为 29 岁（四分位距[IQR] 16 至 44）；大多数参与者报告自己的种族为黑种人（51.5%）或棕色人（41.7%），58.5%为女性。参与家庭的中位数规模为 3 人（IQR 2 至 4），人均日收入中位数为 2.32 美元（IQR 0.33-5.15）。主要结局指标为存在针对 SARS-CoV-2 刺突蛋白的 IgG。我们实施了多水平模型，每个家庭都有随机截距，以估计血清阳性率和相关风险因素，调整了检测的敏感性和特异性，以及我们研究人群的年龄和性别分布。我们发现高血清阳性率（47.9%，95%置信区间[CI] 44.2%至 52.1%），特别是在女性居民中（50.3%[95%CI 46.3%至 54.8%]与男性居民（44.6%[95%CI 40.1%至 49.4%]，p<0.01）和儿童中（54.4%[95%CI 49.6%至 59.3%]与成年人（45.4%[95%CI 41.5%至 49.7%]，p<0.01）。家中有儿童的成年人更有可能呈血清阳性（48.6%[95%CI 44.8%至 52.3%]与 40.7%[95%CI 37.2%至 44.3%]，p<0.01）。与具有相同就业和收入状况的男性相比，失业且生活在贫困线以下（人均家庭日收入<1.25 美元）的女性更有可能呈血清阳性（53.9%[95%CI 47.0%至 60.6%]与 32.9%[95%CI 23.2%至 44.3%]，p<0.01）。研究参与是自愿的，这可能限制了我们研究结果的普遍性。
在 COVID-19 大流行第二波高峰之前，通过血清学评估的累积发病率在巴西一个城市贫民窟人群中接近 50%。与工业化国家的观察结果相反，SARS-CoV-2 的发病率在儿童中最高，其次是生活在极端贫困中的女性。这些发现强调了需要采取有针对性的干预措施，为儿童提供安全的环境，并减轻拥挤和贫困对城市贫民窟社区最脆弱居民构成的结构性风险。
