Southern Community Laboratories, Dunedin, New Zealand; Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.
Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre, University of Auckland, Auckland, New Zealand.
Pathology. 2021 Aug;53(5):645-651. doi: 10.1016/j.pathol.2021.04.001. Epub 2021 May 18.
During New Zealand's first outbreak in early 2020 the Southern Region had the highest per capita SARS-CoV-2 infection rate. Polymerase chain reaction (PCR) testing was initially limited by a narrow case definition and limited laboratory capacity, and cases may have been missed. Our objectives were to evaluate the Abbott SARS-CoV-2 IgG nucleocapsid assay, alongside spike-based assays, and to determine the frequency of antibodies among PCR-confirmed and probable cases, and higher risk individuals in the Southern Region of New Zealand. Pre-pandemic sera (n=300) were used to establish assay specificity and sera from PCR-confirmed SARS-CoV-2 patients (n=78) to establish sensitivity. For prevalence analysis, all samples (n=1214) were tested on the Abbott assay, and all PCR-confirmed cases (n=78), probable cases (n=9), and higher risk individuals with 'grey-zone' (n=14) or positive results (n=11) were tested on four additional SARS-CoV-2 serological assays. The median time from infection onset to serum collection for PCR-confirmed cases was 14 weeks (range 11-17 weeks). The Abbott assay demonstrated a specificity of 99.7% (95% CI 98.2-99.99%) and a sensitivity of 76.9% (95% CI 66.0-85.7%). Spike-based assays demonstrated superior sensitivity ranging 89.7-94.9%. Nine previously undiagnosed sero-positive individuals were identified, and all had epidemiological risk factors. Spike-based assays demonstrated higher sensitivity than the Abbott IgG assay, likely due to temporal differences in antibody persistence. No unexpected SARS-CoV-2 infections were found in the Southern Region of New Zealand, supporting the elimination status of the country at the time this study was conducted.
在 2020 年初新西兰的首次疫情爆发期间，南部地区的 SARS-CoV-2 感染率最高。聚合酶链反应（PCR）检测最初受到严格的病例定义和有限的实验室能力的限制，可能会遗漏病例。我们的目的是评估雅培 SARS-CoV-2 IgG 核衣壳测定法与基于尖峰的测定法，并确定 PCR 确诊和可能病例以及新西兰南部地区高危个体中的抗体频率。使用流行前血清（n=300）来确定测定法的特异性，并用 PCR 确诊的 SARS-CoV-2 患者的血清（n=78）来确定敏感性。为了进行患病率分析，对所有样本（n=1214）均在雅培测定法上进行了检测，对所有 PCR 确诊病例（n=78）、可能病例（n=9）和具有“灰色地带”（n=14）或阳性结果（n=11）的高危个体，均在另外四种 SARS-CoV-2 血清学测定法上进行了检测。PCR 确诊病例血清采集与感染发病之间的中位时间为 14 周（范围为 11-17 周）。雅培测定法的特异性为 99.7%（95%CI 98.2-99.99%），敏感性为 76.9%（95%CI 66.0-85.7%）。基于尖峰的测定法显示出更高的敏感性，范围为 89.7-94.9%。鉴定出 9 例以前未确诊的血清阳性个体，且所有个体均具有流行病学风险因素。基于尖峰的测定法比雅培 IgG 测定法具有更高的敏感性，这可能是由于抗体持续时间的时间差异所致。在新西兰南部地区未发现意外的 SARS-CoV-2 感染，这支持了该研究进行时该国的消除状态。
