Studies of adaptive immunity to SARS-CoV-2 include characterisation of lethal, severe and mild cases. Understanding how long immunity lasts in people who have had mild or asymptomatic infection is crucial. Healthcare worker (HCW) cohorts exposed to and infected by SARS-CoV-2 during the early stages of the pandemic are an invaluable resource to study this question. The UK COVIDsortium is a longitudinal, London hospital HCW cohort, followed from the time of UK lockdown; weekly PCR, serology and symptom diaries allowed capture of asymptomatic infection around the time of onset, so duration of immunity could be tracked. Here, we conduct a cross-sectional, case-control, sub-study of 136 HCW at 16-18 weeks after UK lockdown, with 76 having had laboratory-confirmed SARS-CoV-2 mild or asymptomatic infection. Neutralising antibodies (nAb) were present in 90% of infected HCW sampled after the first wave; titres, likely to correlate with functional protection, were present in 66% at 16-18 weeks. T cell responses tended to be lower in asymptomatic infected HCW than those reporting case-definition symptoms of COVID-19, while nAb titres were maintained irrespective of symptoms. T cell and antibody responses were discordant. HCW lacking nAb also showed undetectable T cells to Spike protein but had T cells of other specificities. Our findings suggest that the majority of HCW with mild or asymptomatic SARS-CoV-2 infection carry nAb complemented by multi-specific T cell responses for at least 4 months after mild or asymptomatic SARS-CoV-2 infection.

中文翻译：

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患有轻度/无症状SARS-CoV-2感染的医护人员在第一波后显示T细胞反应和中和抗体

对SARS-CoV-2的适应性免疫研究包括致死，严重和轻度病例的特征。了解轻度或无症状感染者的免疫力持续时间至关重要。在大流行的早期阶段，暴露于SARS-CoV-2并被其感染的医护人员（HCW）队列是研究此问题的宝贵资源。UK COVIDsortium是纵向的伦敦医院HCW队列，从英国锁定之时起就开始使用。每周进行的PCR，血清学和症状日记可以在发病前后捕获无症状感染，因此可以追踪免疫时间。在这里，我们进行了横断面病例对照亚研究，在英国禁闭后16-18周对136例HCW进行了研究，其中76例在实验室确认为SARS-CoV-2轻度或无症状感染。第一波后采样的90％感染的HCW中存在中和抗体（nAb）；16-18周时，可能与功能保护相关的效价为66％。在无症状感染的HCW中，T细胞应答往往低于报告COVID-19病例定义症状的HCW，而nAb滴度保持不变而与症状无关。T细胞和抗体反应不一致。缺乏nAb的HCW还显示出无法检测到Spike蛋白的T细胞，但具有其他特异性的T细胞。我们的发现表明，轻度或无症状SARS-CoV-2感染后，大多数患有轻度或无症状SARS-CoV-2感染的HCW至少在4个月内携带nAb并伴有多特异性T细胞应答。在16-18周时占66％。在无症状感染的HCW中，T细胞应答往往低于报告COVID-19病例定义症状的HCW，而nAb滴度保持不变而与症状无关。T细胞和抗体反应不一致。缺乏nAb的HCW还显示出无法检测到Spike蛋白的T细胞，但具有其他特异性的T细胞。我们的发现表明，轻度或无症状SARS-CoV-2感染后，大多数患有轻度或无症状SARS-CoV-2感染的HCW至少在4个月内携带nAb并伴有多特异性T细胞应答。在16-18周时占66％。在无症状感染的HCW中，T细胞应答往往低于报告COVID-19病例定义症状的HCW，而nAb滴度保持不变而与症状无关。T细胞和抗体反应不一致。缺乏nAb的HCW还显示出无法检测到Spike蛋白的T细胞，但具有其他特异性的T细胞。我们的发现表明，轻度或无症状SARS-CoV-2感染后，大多数患有轻度或无症状SARS-CoV-2感染的HCW至少在4个月内携带nAb并伴有多特异性T细胞应答。缺乏nAb的HCW还显示出无法检测到Spike蛋白的T细胞，但具有其他特异性的T细胞。我们的发现表明，轻度或无症状SARS-CoV-2感染后，大多数患有轻度或无症状SARS-CoV-2感染的HCW至少在4个月内携带nAb并伴有多特异性T细胞应答。缺乏nAb的HCW还显示出无法检测到Spike蛋白的T细胞，但具有其他特异性的T细胞。我们的发现表明，轻度或无症状SARS-CoV-2感染后，大多数患有轻度或无症状SARS-CoV-2感染的HCW至少在4个月内携带nAb并伴有多特异性T细胞应答。