Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan.
Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan.
Int J Infect Dis. 2021 May;106:176-182. doi: 10.1016/j.ijid.2021.03.040. Epub 2021 Mar 15.
To determine population-based estimates of coronavirus disease 2019 (COVID-19) in a densely populated urban community of Karachi, Pakistan.
Three cross-sectional surveys were conducted in April, June and August 2020 in low- and high-transmission neighbourhoods. Participants were selected at random to provide blood for Elecsys immunoassay for detection of anti-severe acute respiratory syndrome coronavirus-2 antibodies. A Bayesian regression model was used to estimate seroprevalence after adjusting for the demographic characteristics of each district.
In total, 3005 participants from 623 households were enrolled in this study. In Phase 2, adjusted seroprevalence was estimated as 8.7% [95% confidence interval (CI) 5.1-13.1] and 15.1% (95% CI 9.4-21.7) in low- and high-transmission areas, respectively, compared with 0.2% (95% CI 0-0.7) and 0.4% (95% CI 0-1.3) in Phase 1. In Phase 3, it was 12.8% (95% CI 8.3-17.7) and 21.5% (95% CI 15.6-28) in low- and high-transmission areas, respectively. The conditional risk of infection was 0.31 (95% CI 0.16-0.47) and 0.41 (95% CI 0.28-0.52) in low- and high-transmission neighbourhoods, respectively, in Phase 2. Similar trends were observed in Phase 3. Only 5.4% of participants who tested positive for COVID-19 were symptomatic. The infection fatality rate was 1.66%, 0.37% and 0.26% in Phases 1, 2 and 3, respectively.
Continuing rounds of seroprevalence studies will help to improve understanding of secular trends and the extent of infection during the course of the pandemic.
在巴基斯坦卡拉奇人口稠密的城市社区中，确定基于人群的 2019 年冠状病毒病（COVID-19）的估计。
2020 年 4 月、6 月和 8 月在低传播和高传播社区进行了三次横断面调查。随机选择参与者提供血液，以进行 Elecsys 免疫分析法检测抗严重急性呼吸综合征冠状病毒-2 抗体。使用贝叶斯回归模型调整每个区的人口统计学特征后，估算血清流行率。
本研究共纳入 623 户家庭的 3005 名参与者。在第 2 阶段，低传播区和高传播区的调整血清流行率分别估计为 8.7%（95%置信区间[CI]：5.1-13.1）和 15.1%（95% CI：9.4-21.7），而第 1 阶段的流行率分别为 0.2%（95% CI：0-0.7）和 0.4%（95% CI：0-1.3）。在第 3 阶段，低传播区和高传播区的流行率分别为 12.8%（95% CI：8.3-17.7）和 21.5%（95% CI：15.6-28）。第 2 阶段低传播区和高传播区的感染相对风险分别为 0.31（95% CI：0.16-0.47）和 0.41（95% CI：0.28-0.52）。在第 3 阶段观察到类似的趋势。仅 5.4%的 COVID-19 检测阳性的参与者有症状。第 1、2 和 3 阶段的感染病死率分别为 1.66%、0.37%和 0.26%。
持续进行血清流行率研究将有助于更好地了解大流行过程中的季节性趋势和感染程度。
