The clinical features of SARS-CoV-2 infection range from asymptomatic to severe disease with life-threatening complications. Understanding the persistence of immune responses in asymptomatic individuals merit special attention because of their importance in controlling the spread of the infections. We here studied the antibody and T cell responses, and a wide range of inflammation markers, in 56 SARS-CoV-2 antibody-positive individuals, identified by a population screen after the first wave of SARS-CoV-2 infection. These, mostly asymptomatic individuals, were reanalyzed 7-8 months after their infection together with 115 age-matched seronegative controls. We found that 7-8 months after the infection their antibodies to SARS-CoV-2 Nucleocapsid (N) protein declined whereas we found no decrease in the antibodies to Spike receptor-binding domain (S-RBD) when compared to the findings at seropositivity identification. In contrast to antibodies to N protein, the antibodies to S-RBD correlated with the viral neutralization capacity and with CD4⁺ T cell responses as measured by antigen-specific upregulation of CD137 and CD69 markers. Unexpectedly we found the asymptomatic antibody-positive individuals to have increased serum levels of S100A12, TGF-alpha, IL18, and OSM, the markers of activated macrophages-monocytes, suggesting long-term persistent inflammatory effect associated with the viral infection in asymptomatic individuals. Our results support the evidence for the long-term persistence of the inflammation process and the need for post-infection clinical monitoring of SARS-CoV-2 infected asymptomatic individuals.

SARS-CoV-2 感染的临床特征从无症状到具有危及生命的并发症的严重疾病不等。了解无症状个体免疫反应的持续性值得特别关注，因为它们在控制感染传播方面很重要。我们在这里研究了 56 名 SARS-CoV-2 抗体阳性个体的抗体和 T 细胞反应以及广泛的炎症标志物，这些个体是在第一波 SARS-CoV-2 感染后通过人群筛查确定的。这些大多无症状的个体在感染后 7-8 个月与 115 名年龄匹配的血清阴性对照一起进行了重新分析。我们发现感染后 7-8 个月，他们的 SARS-CoV-2 核衣壳 (N) 蛋白抗体下降，而与血清阳性的结果相比，我们发现 Spike 受体结合域 (S-RBD) 的抗体没有减少鉴别。与 N 蛋白抗体相比，S-RBD 抗体与病毒中和能力和 CD4 相关⁺通过 CD137 和 CD69 标志物的抗原特异性上调测量的 T 细胞反应。出乎意料的是，我们发现无症状抗体阳性个体血清 S100A12、TGF-α、IL18 和 OSM（活化巨噬细胞 - 单核细胞的标志物）水平升高，表明与无症状个体的病毒感染相关的长期持续炎症效应。我们的结果支持炎症过程长期持续存在的证据，以及对感染 SARS-CoV-2 的无症状个体进行感染后临床监测的必要性。