Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread within the human population. Although SARS-CoV-2 is a novel coronavirus, most humans had been previously exposed to other antigenically distinct common seasonal human coronaviruses (hCoVs) before the coronavirus disease 2019 (COVID-19) pandemic. Here, we quantified levels of SARS-CoV-2-reactive antibodies and hCoV-reactive antibodies in serum samples collected from 431 humans before the COVID-19 pandemic. We then quantified pre-pandemic antibody levels in serum from a separate cohort of 251 individuals who became PCR-confirmed infected with SARS-CoV-2. Finally, we longitudinally measured hCoV and SARS-CoV-2 antibodies in the serum of hospitalized COVID-19 patients. Our studies indicate that most individuals possessed hCoV-reactive antibodies before the COVID-19 pandemic. We determined that ∼20% of these individuals possessed non-neutralizing antibodies that cross-reacted with SARS-CoV-2 spike and nucleocapsid proteins. These antibodies were not associated with protection against SARS-CoV-2 infections or hospitalizations, but they were boosted upon SARS-CoV-2 infection.

严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 已在人群中迅速传播。尽管 SARS-CoV-2 是一种新型冠状病毒，但大多数人在 2019 年冠状病毒病 (COVID-19) 大流行之前曾接触过其他抗原性不同的常见季节性人类冠状病毒 (hCoV)。在这里，我们量化了 COVID-19 大流行之前从 431 人身上采集的血清样本中 SARS-CoV-2 反应性抗体和 hCoV 反应性抗体的水平。然后，我们对 251 名经 PCR 确认感染 SARS-CoV-2 的个体的单独队列血清中的大流行前抗体水平进行了量化。最后，我们纵向测量了住院 COVID-19 患者血清中的 hCoV 和 SARS-CoV-2 抗体。我们的研究表明，在 COVID-19 大流行之前，大多数人都拥有 hCoV 反应性抗体。我们确定这些人中约有 20% 具有与 SARS-CoV-2 刺突蛋白和核衣壳蛋白发生交叉反应的非中和抗体。这些抗体与预防 SARS-CoV-2 感染或住院治疗无关，但它们在 SARS-CoV-2 感染后得到增强。