Bernard Mathieu, Cosentino Gina, Pieri Laura, Zachary Pierre, Buser Michael, Kbaier Laurent, Giannoli Jean-Marc
BioLittoral-Biogroup, Plateau technique la Bastide, Sanary-sur-Mer, France.
BPO-BioÉpine-Biogroup, Plateau technique Chocolaterie, Levallois-Perret, France, UMR 1173 Inserm, Université Paris-Saclay - UVSQ, Montigny-le-Bretonneux, France.
Ann Biol Clin (Paris). 2021 Apr 1;79(2):168-175. doi: 10.1684/abc.2021.1641.
Discovered in 2019 in the region of Wuhan, China, the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) rapidly established itself as a major pathogenic agent of morbidity and mortality. France has implemented a strategy to fight this virus which relies essentially on widespread RT-PCR virological testing in order to isolate positive patients. Antigenic tests have recently been made available to help the diagnostics. We have conducted a retrospective study to determine the sensitivity of these antigenic tests, comparing them to the reference RT-PCR method.
Between December 7, 2020 and January 31, 2021, each patient we received in our laboratories for an RT-PCR test was enrolled. Out of 271,649 patients, 4,881 had been submitted to an antigenic test (TDR) in the preceding 24 hours. Comparing the data resulting from both tests, we established the sensitivity and the specificity of the antigenic tests. For our analysis we included the parameter of symptom and/or the value of Cycles threshold (Ct) in our parameters.
The sensitivity of the TDRs compared to all the positive RT-PCR tests is 56%. We further demonstrate the correlation between the symptom duration and the reduction of the nasopharyngeal viral load. Based on this data, we have established that the sensitivity of the TDRs decreases very rapidly after symptom onset, contrary to the estimated viral load in the RT-PCR. Indeed, less the 24 hours after clinical symptom onset, the sensitivity of the TDRs decreases from 74% to 60%. By including the Ct value in our parameters, we have established that, despite a high viral load and clinical symptoms since 7 days or less, the sensitivity of the TDRs is 66%. Although, a high number of asymptomatic patients among carriers of SARS-CoV-2, we have estimated a specificity of 93% for our test.
Performance in terms of sensitivity and specificity of the TDR, as assessed in practice, are inferior to those given by the manufacturer, which raises several questions. What is the impact of falsely negative results for patients carrying a high viral load? Are the implemented measures sufficient to prevent the epidemic?
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）于2019年在中国武汉地区被发现，迅速成为导致发病和死亡的主要病原体。法国实施了一项抗击这种病毒的战略，该战略主要依靠广泛的逆转录聚合酶链反应（RT-PCR）病毒学检测来隔离阳性患者。最近已提供抗原检测以辅助诊断。我们进行了一项回顾性研究，以确定这些抗原检测的敏感性，并将其与参考RT-PCR方法进行比较。
在2020年12月7日至2021年1月31日期间，我们实验室接收的每一位进行RT-PCR检测的患者都被纳入研究。在271,649名患者中，有4,881人在之前24小时内接受了抗原检测（TDR）。通过比较两种检测得出的数据，我们确定了抗原检测的敏感性和特异性。在分析中，我们将症状参数和/或循环阈值（Ct）值纳入参数。
与所有阳性RT-PCR检测相比，TDR的敏感性为56%。我们进一步证明了症状持续时间与鼻咽部病毒载量降低之间的相关性。基于这些数据，我们确定，与RT-PCR中估计的病毒载量相反，症状出现后TDR的敏感性迅速下降。事实上，在临床症状出现后不到24小时，TDR的敏感性从74%降至60%。通过将Ct值纳入我们的参数，我们确定，尽管病毒载量高且临床症状持续7天或更短时间，但TDR的敏感性为66%。尽管SARS-CoV-2携带者中有大量无症状患者，但我们估计我们的检测特异性为93%。
实际评估中TDR在敏感性和特异性方面的表现低于制造商给出的结果，这引发了几个问题。对于病毒载量高的患者，假阴性结果有什么影响？所采取的措施是否足以预防疫情？
