Evidence suggests that asymptomatic and mild SARS-CoV-2 infections comprise > 95% of all cases. Developing a test that indicates past infection and possible immunity against the virus is important. We administered 244 antibody tests to three groups of high-risk population. The test consisted of an IgG component and an IgM component. The overall IgM/IgG positivity for patients with none, mild, moderate, and severe symptoms were 21.1%, 21.8%, 14.2%, and 26.9%, respectively. Those with moderate or severe symptoms were no more or less likely to have positive antibody tests than those with no or mild symptoms.

中文翻译：

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加利福尼亚州洛杉矶县的 COVID-19 IgG/IgM 抗体检测

有证据表明，无症状和轻度 SARS-CoV-2 感染占所有病例的 95% 以上。开发一种测试来表明过去的感染情况和可能对病毒的免疫力非常重要。我们对三组高危人群进行了 244 项抗体检测。该测试由 IgG 成分和 IgM 成分组成。无症状、轻度、中度和重度症状患者的总体 IgM/IgG 阳性率分别为 21.1%、21.8%、14.2% 和 26.9%。那些有中度或重度症状的人与没有或轻微症状的人相比，抗体检测呈阳性的可能性并没有增加或减少。