Sibounheuang Bountoy, Boutthasavong Latsaniphone, Chommanam Danoy, Phommasone Koukeo, Panapruksachat Siribun, Praphasiri Viladeth, Bouttavong Sengvong, Sisavath Hongkham, Christy Nathaniel C V, Letizia Andrew G, Mayxay Mayfong, Vongsouvath Manivanh, Ashley Elizabeth A, Dubot-Pérès Audrey
Microbiology Laboratory, Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Lao PDR.
Xiengkhouang Hospital, Xiengkhouang, Lao PDR.
Open Forum Infect Dis. 2024 Jul 23;11(8):ofae433. doi: 10.1093/ofid/ofae433. eCollection 2024 Aug.
Surveillance of SARS-CoV-2 circulation is mainly based on real-time reverse transcription-polymerase chain reaction, which requires laboratory facilities and cold chain for sample transportation. This is difficult to achieve in remote rural areas of resource-limited settings. The use of dried blood spots shipped at room temperature has shown good efficiency for the detection of arboviral RNA. Using a similar approach, we conducted a study at 3 provincial hospitals in Laos to compare the detection of SARS-CoV-2 from neat and dried spot samples.
Between January 2022 and March 2023, patients with respiratory symptoms were recruited. Nasopharyngeal/oropharyngeal swabs in virus transport medium (VTM), dry swabs, saliva, and dried saliva spotted on filter paper were collected. All samples were tested by SARS-CoV-2 real-time reverse transcription-polymerase chain reaction.
In total, 479 participants were included. The VTM samples tested positive for 288 (60.1%). High positive percent agreements were observed for dry swab (84.8%; 95% CI, 80.2%-88.8%) and saliva (89.2%; 95% CI, 85.1%-92.6%) as compared with VTM. There was a loss of sensitivity when saliva was dried on filter paper (73.6%; 95% CI, 68.1%-78.6%) as compared with saliva. SARS-CoV-2 variant (Delta or Omicron) had no significant impact on the performance of the different sample types.
Our findings suggest that dry swabs could be a good alternative for sample collection and permit easy shipping at ambient temperature for subsequent viral SARS-CoV-2 RNA purification and molecular investigation. This is a useful tool to consider for a rapid implementation of large-scale surveillance of SARS-CoV-2 in remote areas, which could be extrapolated to other respiratory targets during routine surveillance or in the case of a novel emerging pandemic.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）传播的监测主要基于实时逆转录-聚合酶链反应，这需要实验室设施和样本运输的冷链。在资源有限地区的偏远农村地区，这很难实现。使用在室温下运输的干血斑已显示出对虫媒病毒RNA检测的良好效率。采用类似方法，我们在老挝的3家省级医院开展了一项研究，以比较从原液样本和干斑样本中检测SARS-CoV-2的情况。
在2022年1月至2023年3月期间招募有呼吸道症状的患者。收集病毒运输培养基（VTM）中的鼻咽/口咽拭子、干拭子、唾液以及滤纸上的干唾液斑。所有样本均通过SARS-CoV-2实时逆转录-聚合酶链反应进行检测。
总共纳入了479名参与者。VTM样本中有288个（60.1%）检测呈阳性。与VTM相比，干拭子（84.8%；95%置信区间，80.2%-88.8%）和唾液（89.2%；95%置信区间，85.1%-92.6%）的阳性百分比一致性较高。与唾液相比，当唾液在滤纸上干燥时敏感性有所降低（73.6%；95%置信区间，68.1%-78.6%）。SARS-CoV-2变异株（德尔塔或奥密克戎）对不同样本类型的检测性能没有显著影响。
我们的研究结果表明，干拭子可能是样本采集的良好替代方法，并且允许在常温下轻松运输，以便随后进行SARS-CoV-2病毒RNA纯化和分子研究。这是在偏远地区快速实施大规模SARS-CoV-2监测时可考虑的有用工具，在常规监测期间或出现新型大流行时，可将其推广到其他呼吸道病原体监测。
