SARS-CoV-2 infection in children is less severe than it is in adults. We perform a longitudinal analysis of the early innate responses in children and adults with mild infection within household clusters. Children display fewer symptoms than adults do, despite similar initial viral load, and mount a robust anti-viral immune signature typical of the SARS-CoV-2 infection and characterized by early interferon gene responses; increases in cytokines, such as CXCL10 and GM-CSF; and changes in blood cell numbers. When compared with adults, the antiviral response resolves faster (within a week of symptoms), monocytes and dendritic cells are more transiently activated, and genes associated with B cell activation appear earlier in children. Nonetheless, these differences do not have major effects on the quality of SARS-CoV-2-specific antibody responses. Our findings reveal that better early control of inflammation as observed in children may be key for rapidly controlling infection and limiting the disease course.

儿童 SARS-CoV-2 感染的严重程度低于成人。我们对家庭群体中轻度感染的儿童和成人的早期先天反应进行了纵向分析。尽管初始病毒载量相似，但儿童表现出的症状比成人少，并且具有 SARS-CoV-2 感染典型的强大抗病毒免疫特征，其特征是早期干扰素基因反应；细胞因子增加，例如 CXCL10 和 GM-CSF；和血细胞数量的变化。与成人相比，儿童的抗病毒反应消退得更快（症状出现一周内），单核细胞和树突状细胞被更短暂地激活，与 B 细胞激活相关的基因出现得更早。尽管如此，这些差异并未对 SARS-CoV-2 特异性抗体反应的质量产生重大影响。我们的研究结果表明，在儿童中观察到的更好的早期炎症控制可能是快速控制感染和限制病程的关键。