Department of Infectious Diseases, Asan Medical Center, Songpa-gu, Seoul, Republic of Korea.
Clinical Research Center, Asan Institute for Life Sciences, Asan Medical Center, Songpa-gu, Seoul, Republic of Korea.
Thorax. 2021 Jan;76(1):61-63. doi: 10.1136/thoraxjnl-2020-215042. Epub 2020 Sep 22.
Asymptomatic individuals with SARS-CoV-2 infection have viable viral loads and have been linked to several transmission cases. However, data on the viral loads in such individuals are lacking. We assessed the viral loads in asymptomatic individuals with SARS-CoV-2 infection in comparison with those in symptomatic patients with COVID-19.
Study participants were recruited from a community facility designated for the isolation of patients with mild COVID-19 in South Korea. The presence of symptoms was evaluated with a questionnaire-based survey. Viral loads in the upper respiratory tract were measured with real-time reverse transcription-PCR (RT-PCR) targeting the , and genes of SARS-CoV-2, with a cycle threshold (Ct) value of 40 for determining positivity.
In 213 patients with SARS-CoV-2 infection, 41 (19%) had remained asymptomatic from potential exposure to laboratory confirmation and admission; of them, 39 (95%) underwent follow-up RT-PCR testing after a median 13 days. In 172 symptomatic patients, 144 (84%) underwent follow-up RT-PCR testing. Twenty-one (54%) asymptomatic individuals and 92 (64%) symptomatic patients tested positive for SARS-CoV-2 at follow-up. Asymptomatic individuals and symptomatic patients did not show any significant differences in the mean Ct values of the (31.15 vs 31.43; p>0.99), (32.26 vs 32.93; p=0.92) and (33.05 vs 33.28; p>0.99) genes.
Approximately one-fifth of the individuals without severe symptoms were asymptomatic, and their viral loads were comparable to those in symptomatic patients. A large proportion of mildly symptomatic patients with COVID-19 or asymptomatic individuals with SARS-CoV-2 showed persistent positive upper respiratory RT-PCR results at follow-up.
无症状的 SARS-CoV-2 感染者具有存活的病毒载量，并与几例传播病例有关。然而，此类个体的病毒载量数据尚不清楚。我们评估了无症状 SARS-CoV-2 感染者与有症状的 COVID-19 患者的病毒载量。
研究参与者是从韩国一家指定用于隔离轻症 COVID-19 患者的社区机构招募的。通过基于问卷的调查评估症状的存在。使用针对 SARS-CoV-2 的 、 和 基因的实时逆转录-PCR（RT-PCR）测量上呼吸道的病毒载量，以 40 的循环阈值（Ct）值确定阳性。
在 213 例 SARS-CoV-2 感染患者中，有 41 例（19%）从潜在暴露到实验室确认和入院时一直无症状；其中 39 例（95%）在中位随访 13 天后接受了后续 RT-PCR 检测。在 172 例有症状的患者中，有 144 例（84%）接受了后续 RT-PCR 检测。21 例（54%）无症状个体和 92 例（64%）有症状患者在随访时 SARS-CoV-2 检测呈阳性。无症状个体和有症状患者的 、 和 基因的平均 Ct 值无显著差异（31.15 对 31.43；p>0.99）、（32.26 对 32.93；p=0.92）和（33.05 对 33.28；p>0.99）。
约五分之一无严重症状的个体无症状，其病毒载量与有症状患者相当。相当一部分 COVID-19 症状轻微的患者或 SARS-CoV-2 无症状个体在随访时上呼吸道 RT-PCR 结果持续呈阳性。
