Department of Epidemiology and Biostatistics, University of Maryland School of Public Health, College Park, Maryland, USA.
Public Health Aerobiology and Biomarker Laboratory, Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, Maryland, USA.
Microbiol Spectr. 2022 Apr 27;10(2):e0012822. doi: 10.1128/spectrum.00128-22. Epub 2022 Mar 21.
Saliva is an attractive sample for detecting SARS-CoV-2. However, contradictory reports exist concerning the sensitivity of saliva versus nasal swabs. We followed close contacts of COVID-19 cases for up to 14 days from the last exposure and collected self-reported symptoms, midturbinate swabs (MTS), and saliva every 2 or 3 days. Ct values, viral load, and frequency of viral detection by MTS and saliva were compared. Fifty-eight contacts provided 200 saliva-MTS pairs, and 14 contacts (13 with symptoms) had one or more positive samples. Saliva and MTS had similar rates of viral detection ( = 0.78) and substantial agreement (κ = 0.83). However, sensitivity varied significantly with time since symptom onset. Early on (days -3 to 2), saliva had 12 times (95% CI: 1.2, 130) greater likelihood of viral detection and 3.2 times (95% CI: 2.8, 3.8) higher RNA copy numbers compared to MTS. After day 2 of symptoms, there was a nonsignificant trend toward greater sensitivity using MTS. Saliva and MTS demonstrated high agreement making saliva a suitable alternative to MTS for SARS-CoV-2 detection. Saliva was more sensitive early in the infection when the transmission was most likely to occur, suggesting that it may be a superior and cost-effective screening tool for COVID-19. The findings of this manuscript are increasingly important with new variants that appear to have shorter incubation periods emerging, which may be more prone to detection in saliva before detection in nasal swabs. Therefore, there is an urgent need to provide the science to support the use of a detection method that is highly sensitive and widely acceptable to the public to improve screening rates and early detection. The manuscript presents the first evidence that saliva-based RT-PCR is more sensitive than MTS-based RT-PCR in detecting SARS-CoV-2 during the presymptomatic period - the critical period for unwitting onward transmission. Considering other advantages of saliva samples, including the lower cost, greater acceptability within the general population, and less risk to health care workers, our findings further supported the use of saliva to identify presymptomatic infection and prevent transmission of the virus.
唾液是检测 SARS-CoV-2 的有吸引力的样本。然而，关于唾液与鼻拭子的敏感性存在相互矛盾的报告。我们对 COVID-19 病例的密切接触者进行了长达 14 天的随访，从最后一次接触之日起每 2 至 3 天收集自我报告的症状、中鼻甲拭子（MTS）和唾液。比较了 Ct 值、病毒载量以及 MTS 和唾液的病毒检测频率。58 名接触者提供了 200 对唾液-MTS 样本，14 名接触者（13 名有症状）有一个或多个阳性样本。唾液和 MTS 的病毒检测率相似（=0.78），具有高度一致性（κ=0.83）。然而，敏感性随症状出现时间的不同而显著变化。早期（-3 至 2 天），与 MTS 相比，唾液检测病毒的可能性高 12 倍（95%CI：1.2，130），RNA 拷贝数高 3.2 倍（95%CI：2.8，3.8）。症状出现后第 2 天，使用 MTS 的敏感性呈无显著趋势。唾液和 MTS 具有高度一致性，使唾液成为 SARS-CoV-2 检测的 MTS 的合适替代品。在感染早期，当传播最有可能发生时，唾液更敏感，这表明它可能是 COVID-19 的一种更好、更具成本效益的筛查工具。随着似乎潜伏期更短的新变体的出现，本研究结果变得越来越重要，这可能使唾液比鼻拭子更易于检测。因此，迫切需要提供科学依据，支持使用一种高度敏感且公众广泛接受的检测方法，以提高筛查率和早期检测。本文首次提供证据表明，在无症状期（即无意识传播的关键时期），基于唾液的 RT-PCR 比基于 MTS 的 RT-PCR 更能检测 SARS-CoV-2。考虑到唾液样本的其他优势，包括成本更低、更受普通人群接受、对医护人员的风险更小，我们的研究结果进一步支持使用唾液来识别无症状感染并防止病毒传播。
