Department of Epidemiology and Global Health, Institut National de Recherche Biomédicale, Faculty of Medicine, University of Kikwit, Kinshasa, Democratic Republic of Congo.
Department of Epidemiology and Global Health, Institut National de Recherche Biomédicale & Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo.
J Health Popul Nutr. 2024 Jun 1;43(1):74. doi: 10.1186/s41043-024-00536-0.
Serological surveys offer the most direct measurement to define the immunity status for numerous infectious diseases, such as COVID-19, and can provide valuable insights into understanding transmission patterns. This study describes seroprevalence changes over time in the context of the Democratic Republic of Congo, where COVID-19 case presentation was apparently largely oligo- or asymptomatic, and vaccination coverage remained extremely low.
A cohort of 635 health care workers (HCW) from 5 health zones of Kinshasa and 670 of their household members was interviewed and sampled in 6 rounds between July 2020 and January 2022. At each round, information on risk exposure and a blood sample were collected. Serology was defined as positive when binding antibodies against SARS-CoV-2 spike and nucleocapsid proteins were simultaneously present.
The SARS-CoV-2 antibody seroprevalence was high at baseline, 17.3% (95% CI 14.4-20.6) and 7.8% (95% CI 5.5-10.8) for HCW and household members, respectively, and fluctuated over time, between 9% and 62.1%. Seropositivity was heterogeneously distributed over the health zones (p < 0.001), ranging from 12.5% (95% CI 6.6-20.8) in N'djili to 33.7% (95% CI 24.6-43.8) in Bandalungwa at baseline for HCW. Seropositivity was associated with increasing rounds adjusted Odds Ratio (aOR) 1.75 (95% CI 1.66-1.85), with increasing age aOR 1.11 (95% CI 1.02-1.20), being a female aOR 1.35 (95% CI 1.10-1.66) and being a HCW aOR 2.38 (95% CI 1.80-3.14). There was no evidence that HCW brought the COVID-19 infection back home, with an aOR of 0.64 (95% CI 0.46-0.91) of seropositivity risk among household members in subsequent surveys. There was seroreversion and seroconversion over time, and HCW had a lower risk of seroreverting than household members (aOR 0.60 (95% CI 0.42-0.86)).
SARS-CoV-2 IgG antibody levels were high and dynamic over time in this African setting with low clinical case rates. The absence of association with health profession or general risk behaviors and with HCW positivity in subsequent rounds in HH members, shows the importance of the time-dependent, and not work-related, force of infection. Cohort seroprevalence estimates in a 'new disease' epidemic seem insufficient to guide policy makers for defining control strategies.
血清学调查提供了最直接的测量方法来定义许多传染病（如 COVID-19）的免疫状态，并能深入了解传播模式。本研究描述了刚果民主共和国的血清流行率变化情况，该国的 COVID-19 病例表现明显主要是少或无症状，疫苗接种率仍然极低。
2020 年 7 月至 2022 年 1 月期间，共对来自金沙萨的 5 个卫生区的 635 名卫生保健工作者（HCW）及其 670 名家庭成员进行了 6 轮访谈和抽样。每一轮都收集了风险暴露信息和血样。当 SARS-CoV-2 刺突蛋白和核衣壳蛋白的结合抗体同时存在时，将血清学定义为阳性。
HCW 和家庭成员的 SARS-CoV-2 抗体血清阳性率在基线时很高，分别为 17.3%（95%CI 14.4-20.6）和 7.8%（95%CI 5.5-10.8），并且随着时间的推移而波动，在 9%至 62.1%之间。血清阳性率在卫生区之间呈异质分布（p<0.001），在基线时，N'djili 为 12.5%（95%CI 6.6-20.8），Bandalungwa 为 33.7%（95%CI 24.6-43.8）。调整后的优势比（aOR）1.75（95%CI 1.66-1.85）随轮次增加而增加，年龄每增加 1 岁 aOR 增加 1.11（95%CI 1.02-1.20），女性 aOR 增加 1.35（95%CI 1.10-1.66），HCW aOR 增加 2.38（95%CI 1.80-3.14）。没有证据表明 HCW 将 COVID-19 感染带回家庭，随后调查中家庭接触者的血清阳性风险 aOR 为 0.64（95%CI 0.46-0.91）。随着时间的推移，出现了血清学逆转和血清学转换，HCW 的血清学逆转风险低于家庭接触者（aOR 0.60（95%CI 0.42-0.86））。
在这个临床病例率较低的非洲环境中，SARS-CoV-2 IgG 抗体水平随着时间的推移而升高且动态变化。与卫生职业或一般风险行为以及随后轮次中 HCW 的阳性率无关，表明感染的时间依赖性而非与工作相关的力很重要。在“新疾病”流行中，队列血清流行率估计不足以指导决策者制定控制策略。
