Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan, China.
State Key Laboratory of Virology, School of Basic Medical Sciences, Wuhan University, Wuhan, China.
mSphere. 2020 Oct 7;5(5):e00922-20. doi: 10.1128/mSphere.00922-20.
Since the outbreak of coronavirus disease 2019 (COVID-19) in Wuhan, China, it has rapidly spread around the world. Persons with asymptomatic disease exhibit viral shedding, resulting in transmission, which presents disease control challenges. However, the clinical characteristics of these asymptomatic individuals remain elusive. We collected samples of 25 asymptomatic and 27 symptomatic COVID-19 patients. Viral titers of throat swabs were determined by quantitative reverse transcription-PCR (qRT-PCR). COVID-19 IgG and IgM were examined. Complete blood counts were determined, and serum biochemistry panels were performed. Cytokines, including gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin 2 (IL-2), IL-4, IL-6, and IL-10 were evaluated. T cell, B cell, and NK cell counts were measured using flow cytometry. Although similar viral loads were detected, asymptomatic patients had significantly faster virus turnover than symptomatic patients. Additionally, asymptomatic patients had higher counts of lymphocytes, T cells, B cells, and NK cells. While liver damage was observed in symptomatic patients, as indicated by elevated liver enzymes and decreased liver-synthesized proteins in the blood, asymptomatic patients showed normal liver measurements. Lactate dehydrogenase, a COVID-19 risk factor, was significantly lower in asymptomatic patients. These results suggest that asymptomatic COVID-19 patients had normal clinical indicators and faster viral clearance than symptomatic patients. Lymphocytes may play a role in their asymptomatic phenotype. Since asymptomatic patients may be a greater risk of virus transmission than symptomatic patients, public health interventions and a broader range of testing may be necessary for the control of COVID-19. Asymptomatic transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a potential problem for pandemic control through public health strategies. Our results demonstrate that asymptomatic COVID-19 patients have better outcomes than symptomatic patients. This may have been due to more active cellular immune responses and normal liver function. Since asymptomatic patients have no clinical symptoms which can easily prevent timely diagnosis and treatment, they may cause a greater risk of virus transmission than symptomatic patients, which poses a major challenge to infection control. Evidence suggests that nonpharmaceutical public health interventions, like social distancing and face mask ordinances, play important roles in the control of COVID-19. Looking forward, it may be necessary to proceed cautiously while reopening businesses in areas of epidemicity to prevent potential waves of COVID-19 in the future.
自 2019 年中国武汉爆发冠状病毒病（COVID-19）以来，该病毒迅速在全球范围内传播。无症状疾病患者表现出病毒脱落，导致传播，这给疾病控制带来了挑战。然而，这些无症状个体的临床特征仍然难以捉摸。我们收集了 25 例无症状和 27 例有症状 COVID-19 患者的样本。通过定量逆转录-PCR（qRT-PCR）测定咽拭子的病毒滴度。检查 COVID-19 IgG 和 IgM。测定全血细胞计数，并进行血清生化分析。评估细胞因子，包括γ干扰素（IFN-γ）、肿瘤坏死因子-α（TNF-α）、白细胞介素 2（IL-2）、IL-4、IL-6 和 IL-10。使用流式细胞术测量 T 细胞、B 细胞和 NK 细胞计数。尽管检测到相似的病毒载量，但无症状患者的病毒周转速度明显快于有症状患者。此外，无症状患者的淋巴细胞、T 细胞、B 细胞和 NK 细胞计数较高。虽然有症状患者的肝脏酶升高和血液中合成的肝脏蛋白减少表明存在肝损伤，但无症状患者的肝脏测量值正常。乳酸脱氢酶是 COVID-19 的一个危险因素，在无症状患者中明显较低。这些结果表明，无症状 COVID-19 患者的临床指标正常，病毒清除速度快于有症状患者。淋巴细胞可能在其无症状表型中起作用。由于无症状患者的病毒传播风险可能大于有症状患者，因此可能需要进行公共卫生干预和更广泛的检测，以控制 COVID-19。严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）的无症状传播是通过公共卫生策略控制大流行的一个潜在问题。我们的结果表明，无症状 COVID-19 患者的预后好于有症状患者。这可能是由于更活跃的细胞免疫反应和正常的肝功能。由于无症状患者没有临床症状，容易延误及时诊断和治疗，因此他们的病毒传播风险可能大于有症状患者，这对感染控制构成了重大挑战。有证据表明，非药物公共卫生干预措施，如社会隔离和口罩规定，在 COVID-19 控制中发挥着重要作用。展望未来，在疫情地区重新开放企业时，可能需要谨慎行事，以防止未来 COVID-19 出现潜在浪潮。
