Background

Currently, PCR assay is a golden standard for diagnosis of Covid-19. However, it needs nasopharyngeal swabs, expensive instruments and expertise. It even causes PCR errors.

Methods

We validated the antibody assay (Roche) in 36 followed patients and 1879 controls (medical staffs).

Results

Of 1879 medical staffs, only two (0.11%) were positive by Cut off Index (COI; 1.0) (mean ± SD, 0.094 ± 0.047). Thirty six patients were composed of three groups; Group A,4 from Diamond Princess cruise ship, Group B, 2 infected in Africa, and Group C, 30 infected in Japan. PCR assays were conducted at outside laboratories before and repeated in house after hospitalized. Of 36 at admission, positive antibody was seen in 4/4 from the ship, 0/2 from Africa, and 5/30 from Japan. Two from Africa showed the increase of COI and became positive on days 8 and 13. Thirty Japanese was divided in two groups, e.g., 23 showed dynamic increase of COI up to 84.4 within 3 days while active virus replication present (Group C). In remaining 7 (7/30, 23%) (Group C'), no rise of antibody nor positive in house PCR assays, indicative of false positive results of PCR at the beginning.

Conclusion

This antibody testing has a wide dynamic ranges of COI and, thus, could be utilized in the early infection phase. This may also compliment and even help to avoid possible PCR errors. Therefore, this can serve as a powerful diagnostic tool, needed in the frontline of the clinic and hospitals.

中文翻译：

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针对 Covid-19 的抗体指数的动态变化是早期感染和挽救 PCR 检测错误的强大诊断工具

背景

目前，PCR 检测是诊断 Covid-19 的金标准。然而，它需要鼻咽拭子、昂贵的仪器和专业知识。它甚至会导致 PCR 错误。

方法

我们在 36 名随访患者和 1879 名对照（医务人员）中验证了抗体检测 (Roche)。

结果

在 1879 名医务人员中，只有 2 名（0.11%）的截止指数（COI；1.0）呈阳性（平均值±标准差，0.094±0.047）。三十六名患者分为三组；钻石公主号游轮A组4人，B组非洲2人感染，C组30人日本感染。PCR 检测在住院前在外部实验室进行，并在住院后在室内重复进行。入院时 36 人中，4/4 来自船上，0/2 来自非洲，5/30 来自日本。来自非洲的两个表现出COI增加并在第8天和第13天变为阳性。30个日本人被分成两组，例如23个表现出在3天内COI动态增加到84.4，同时存在活跃的病毒复制（C组）。其余7人（7/30，23%）（C'组），抗体未升高，内部阳性 PCR 检测，指示 PCR 开始时的假阳性结果。

结论

这种抗体测试具有广泛的 COI 动态范围，因此可用于早期感染阶段。这也可以补充甚至有助于避免可能的 PCR 错误。因此，这可以作为一种强大的诊断工具，是诊所和医院前线所需要的。