BACKGROUND: SARS-CoV-2 serological testing has seen extensive academic and clinical use from investigating correlates of immunity to seroprevalence, convalescent plasma and vaccine trials. Interpretation of these studies will depend on robust validation of the longitudinal sensitivities of these assays, especially in the context of mild disease which makes up the majority of the Coronavirus Disease 2019 (COVID-19) caseload.

METHODS: Hospital staff (n=94) returning to work following polymerase chain reaction (PCR) confirmed COVID-19 were offered antibody testing to assist with laboratory verification. Initial specimens were collected at median 29 days post-symptom onset and run on the Roche, Abbott, Siemens and DiaSorin platforms. Re-sampling occurred at median 142 days from a subset of the initial cohort (n=62) that had volunteered to provide further sera to assist in longitudinal sensitivity analysis. Samples that were not run across all four platforms were excluded from analysis.

RESULTS: Comparative sensitivity analysis was conducted on 89/94 of the initial specimens and 55/62 of the repeat specimens. Sensitivity at initial sampling ranged from 78-87% across platforms. At re-sampling, sensitivities were: 100% (Roche), 45% (Abbott), 100% (Siemens), and 80% (DiaSorin). Paired analysis using the longitudinal cohort (n=55) demonstrated stable or increasing median assay values on three platforms, with a clear reduction seen only on the Abbott platform (4.78 to 1.34) with corresponding sensitivity drop-off (81.8% to 45.4%).

CONCLUSION: The Abbott assay demonstrated sensitivity drop-off and decrease in median assay signal below detection threshold at 4-5 months. This has implications on the interpretation and design of future studies.

背景：SARS-CoV-2 血清学检测在研究免疫与血清阳性率、恢复期血浆和疫苗试验的相关性方面得到了广泛的学术和临床应用。这些研究的解释将取决于对这些测定的纵向敏感性的有力验证，特别是在构成 2019 年冠状病毒病 (COVID-19) 病例的大部分的轻度疾病的情况下。

方法：在聚合酶链反应 (PCR) 确认 COVID-19 后返回工作的医院工作人员（n = 94）接受了抗体测试以协助实验室验证。在出现症状后中位数 29 天收集初始样本，并在 Roche、Abbott、Siemens 和 DiaSorin 平台上运行。从自愿提供进一步血清以协助纵向敏感性分析的初始队列的子集（n = 62）中位时间为 142 天进行重新采样。未在所有四个平台上运行的样品被排除在分析之外。

结果：对 89/94 的初始样本和 55/62 的重复样本进行了比较敏感性分析。跨平台初始采样的灵敏度范围为 78-87%。重新采样时，灵敏度为：100% (Roche)、45% (Abbott)、100% (Siemens) 和 80% (DiaSorin)。使用纵向队列 (n=55) 的配对分析表明，三个平台上的中值测定值稳定或增加，仅在雅培平台上观察到明显降低（4.78 至 1.34），相应的灵敏度下降（81.8% 至 45.4%） .

结论：Abbott 检测表明在 4-5 个月时灵敏度下降，中值检测信号低于检测阈值。这对未来研究的解释和设计有影响。