SARS-CoV-2 antibody assays are used for epidemiological studies and for the assessment of vaccine responses in highly vulnerable patients. So far, data on cross-reactivity of SARS-CoV-2 antibody assays is limited. Here, we compared four enzyme-linked immunosorbent assays (ELISAs; Vircell SARS-CoV-2 IgM/IgA and IgG, Euroimmun SARS-CoV-2 IgA and IgG) for detection of anti-SARS-CoV-2 antibodies in 207 patients with COVID-19, 178 patients with serological evidence of different bacterial infections, 107 patients with confirmed viral respiratory disease, and 80 controls from the pre-COVID-19 era. In COVID-19 patients, the assays showed highest sensitivity in week 3 (Vircell-IgM/A and Euroimmun-IgA: 78.9% each) and after week 7 (Vircell-IgG: 97.9%; Euroimmun-IgG: 92.1%). The antibody indices were higher in patients with fatal disease. In general, IgM/IgA assays had only limited or no benefit over IgG assays. In patients with non-SARS-CoV-2 respiratory infections, IgG assays were more specific than IgM/IgA assays, and bacterial infections were associated with more false-positive results than viral infections. The specificities in bacterial and viral infections were 68.0 and 81.3% (Vircell-IgM/IgA), 84.8 and 96.3% (Euroimmun-IgA), 97.8 and 86.0% (Vircell-IgG), and 97.8 and 99.1% (Euroimmun-IgG), respectively. Sera from patients positive for antibodies against Mycoplasma pneumoniae, Chlamydia psittaci, and Legionella pneumophila yielded particularly high rates of unspecific false-positive results in the IgM/IgA assays, which was revealed by applying a highly specific flow-cytometric assay using HEK 293 T cells expressing the SARS-CoV-2 spike protein. Positive results obtained with anti-SARS-CoV-2 IgM/IgA ELISAs require careful interpretation, especially if there is evidence for prior bacterial respiratory infections.

SARS-CoV-2 抗体检测用于流行病学研究和评估高度脆弱患者的疫苗反应。到目前为止，关于 SARS-CoV-2 抗体检测交叉反应的数据是有限的。在这里，我们比较了四种酶联免疫吸附试验（ELISA；Vircell SARS-CoV-2 IgM/IgA 和 IgG、Euroimmun SARS-CoV-2 IgA 和 IgG）以检测 207 名患有 SARS-CoV-2 抗体的患者。 COVID-19、178 名具有不同细菌感染血清学证据的患者、107 名确诊为病毒性呼吸道疾病的患者以及 80 名来自 COVID-19 前时代的对照者。在 COVID-19 患者中，检测在第 3 周（Vircell-IgM/A 和 Euroimmun-IgA：78.9%）和第 7 周后（Vircell-IgG：97.9%；Euroimmun-IgG：92.1%）显示出最高的灵敏度。致命疾病患者的抗体指数较高。一般来说，IgM/IgA 检测与 IgG 检测相比仅具有有限的优势或没有优势。在非 SARS-CoV-2 呼吸道感染患者中，IgG 检测比 IgM/IgA 检测更具特异性，细菌感染比病毒感染导致更多的假阳性结果。细菌和病毒感染的特异性分别为 68.0% 和 81.3% (Vircell-IgM/IgA)、84.8% 和 96.3% (Euroimmun-IgA)、97.8% 和 86.0% (Vircell-IgG) 以及 97.8% 和 99.1% (Euroimmun-IgG) ， 分别。抗体阳性患者的血清 分别为 3% (Vircell-IgM/IgA)、84.8% 和 96.3% (Euroimmun-IgA)、97.8% 和 86.0% (Vircell-IgG) 以及 97.8% 和 99.1% (Euroimmun-IgG)。抗体阳性患者的血清 分别为 3% (Vircell-IgM/IgA)、84.8% 和 96.3% (Euroimmun-IgA)、97.8% 和 86.0% (Vircell-IgG) 以及 97.8% 和 99.1% (Euroimmun-IgG)。抗体阳性患者的血清肺炎支原体、鹦鹉热衣原体和嗜肺军团菌在 IgM/IgA 检测中产生了特别高的非特异性假阳性结果，这是通过使用表达 SARS-CoV-2 的 HEK 293 T 细胞应用高度特异性流式细胞术检测发现的刺突蛋白。使用抗 SARS-CoV-2 IgM/IgA ELISA 获得的阳性结果需要仔细解释，特别是如果有先前细菌呼吸道感染的证据。