King Kylie L, Wilson Stevin, Napolitano Justin M, Sell Keegan J, Rennert Lior, Parkinson Christopher L, Dean Delphine
Center for Innovative Medical Devices and Sensors (REDDI Lab), Clemson University, Clemson, South Carolina, United States of America.
Clemson University Genomics and Bioinformatics Facility, Clemson, South Carolina, United States of America.
medRxiv. 2022 Mar 24:2022.02.10.22270797. doi: 10.1101/2022.02.10.22270797.
Higher viral loads in SARS-CoV-2 infections may be linked to more rapid spread of emerging variants of concern (VOC). Rapid detection and isolation of cases with highest viral loads, even in pre- or asymptomatic individuals, is essential for the mitigation of community outbreaks.
In this study, we analyze Ct values from 1297 SARS-CoV-2 positive patient saliva samples collected at the Clemson University testing lab in upstate South Carolina. Samples were identified as positive using RT-qPCR, and clade information was determined via whole genome sequencing at nearby commercial labs. We also obtained patient-reported information on symptoms and exposures at the time of testing. The lowest Ct values were observed among those infected with Delta (median: 22.61, IQR: 16.72-28.51), followed by Alpha (23.93, 18.36-28.49), Gamma (24.74, 18.84-30.64), and the more historic clade 20G (25.21, 20.50-29.916). There was a statistically significant difference in Ct value between Delta and all other clades (all p.adj<0.01), as well as between Alpha and 20G (p.adj<0.05). Additionally, pre- or asymptomatic patients (n=1093) showed the same statistical differences between Delta and all other clades (all p.adj<0.01); however, symptomatic patients (n=167) did not show any significant differences between clades. Our weekly testing strategy ensures that cases are caught earlier in the infection cycle, often before symptoms are present, reducing this sample size in our population.
COVID-19 variants Alpha and Delta have substantially higher viral loads in saliva compared to more historic clades. This trend is especially observed in individuals who are pre- or asymptomatic, which provides evidence supporting higher transmissibility and more rapid spread of emerging variants. Understanding the viral load of variants spreading within a community can inform public policy and clinical decision making.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染中较高的病毒载量可能与值得关注的新出现变异株（VOC）更快的传播有关。即使在症状出现前或无症状个体中，快速检测和隔离病毒载量最高的病例对于减轻社区疫情至关重要。
在本研究中，我们分析了在南卡罗来纳州北部克莱姆森大学检测实验室收集的1297份SARS-CoV-2阳性患者唾液样本的Ct值。样本通过逆转录定量聚合酶链反应（RT-qPCR）鉴定为阳性，并通过附近商业实验室的全基因组测序确定进化枝信息。我们还获得了患者报告的检测时症状和暴露情况的信息。在感染德尔塔变异株的患者中观察到最低的Ct值（中位数：22.61，四分位距：16.72 - 28.51），其次是阿尔法变异株（23.93，18.36 - 28.49）、伽马变异株（24.74，18.84 - 30.64）以及更早期的20G进化枝（25.21，20.50 - 29.916）。德尔塔变异株与所有其他进化枝之间的Ct值存在统计学显著差异（所有校正P值<0.01），阿尔法变异株与20G进化枝之间也存在差异（校正P值<0.05）。此外，症状出现前或无症状患者（n = 1093）中，德尔塔变异株与所有其他进化枝之间显示出相同的统计学差异（所有校正P值<0.01）；然而，有症状患者（n = 167）中各进化枝之间未显示出任何显著差异。我们的每周检测策略确保在感染周期中更早发现病例，通常在症状出现之前，从而减少了我们人群中的样本量。
与更早期的进化枝相比，新冠病毒变异株阿尔法和德尔塔在唾液中的病毒载量显著更高。这种趋势在症状出现前或无症状个体中尤其明显，这为新出现变异株更高的传播性和更快的传播速度提供了证据。了解在社区中传播的变异株的病毒载量可为公共政策和临床决策提供参考。
