Department of Molecular Biology, Institute of Translational Research, Asian Healthcare Foundation, AIG Hospitals, Survey No 136, Plot No 2/3/4/5, 1, Mindspace Road, Gachibowli, Hyderabad, Telangana, 500032, India.
Department of Microbiology, AIG Hospitals, Survey No 136, Plot No 2/3/4/5, 1, Mindspace Road, Gachibowli, Hyderabad, Telangana, 500032, India.
BMC Infect Dis. 2021 Jul 5;21(1):648. doi: 10.1186/s12879-021-06343-w.
A considerable amount of evidence demonstrates the potential of saliva in the diagnosis of COVID-19. Our aim was to determine the sensitivity of saliva versus swabs collected by healthcare workers (HCWs) and patients themselves to assess whether saliva detection can be offered as a cost-effective, risk-free method of SARS-CoV-2 detection.
This study was conducted in a hospital involving outpatients and hospitalized patients. A total of 3018 outpatients were tested. Of these, 200 qRT-PCR-confirmed SARS-CoV-2-positive patients were recruited for further study. In addition, 101 SARS-CoV-2-positive hospitalized patients with symptoms were also enrolled in the study. From outpatients, HCWs collected nasopharyngeal swabs (NPS), saliva were obtained. From inpatients, HCWs collected swabs, patient-collected swabs, and saliva were obtained. qRT-PCR was performed to detect SARS-CoV-2 by TAQPATH assay to determine the sensitivity of saliva detection. Sensitivity, specificity and positive/negative predictive values (PPV, NPV) of detecting SARS-CoV-2 were calculated using MedCalc.
Of 3018 outpatients (asymptomatic: 2683, symptomatic: 335) tested by qRT-PCR, 200 were positive (males: 140, females: 60; aged 37.9 ± 12.8 years; (81 asymptomatic, 119 symptomatic). Of these, saliva was positive in 128 (64%); 39 of 81 asymptomatic (47%),89 of 119 symptomatic patients (74.8%). Sensitivity of detection was 60.9% (55.4-66.3%, CI 95%), with a negative predictive value of 36%(32.9-39.2%, CI 95%).Among 101 hospitalized patients (males:65, females: 36; aged 53.48 ± 15.6 years), with HCW collected NPS as comparator, sensitivity of saliva was 56.1% (47.5-64.5, CI 95%), specificity 63.5%(50.4-75.3, CI95%) with PPV of 77.2% and NPV of 39.6% and that of self-swab was 52.3%(44-60.5%, CI95%), specificity 56.6% (42.3-70.2%, CI95%) with PPV 77.2% and NPV29.7%. Comparison of positivity with the onset of symptoms revealed highest detection in saliva on day 3 after onset of symptoms. Additionally, only saliva was positive in 13 (12.8%) hospitalized patients.
Saliva which is easier to collect than nasopharyngeal swab is a viable alternate to detect SARS-COV-2 in symptomatic patients in the early stage of onset of symptoms. Although saliva is currently not recommended for screening asymptomatic patients, optimization of collection and uniform timing of sampling might improve the sensitivity enabling its use as a screening tool at community level.
大量证据表明唾液在 COVID-19 的诊断中有一定作用。我们旨在确定唾液检测与医护人员（HCWs）和患者自身采集的拭子检测的灵敏度，以评估唾液检测是否可以作为一种具有成本效益且无风险的 SARS-CoV-2 检测方法。
这项研究在一家医院进行，涉及门诊和住院患者。共对 3018 名门诊患者进行了检测。其中，200 名经 qRT-PCR 确认为 SARS-CoV-2 阳性的患者被纳入进一步研究。此外，还招募了 101 名有症状的 SARS-CoV-2 阳性住院患者。门诊患者由 HCWs 采集鼻咽拭子（NPS），采集唾液。住院患者由 HCWs 采集拭子、患者采集拭子和唾液。使用 TAQPATH 检测试剂盒进行 qRT-PCR 检测 SARS-CoV-2，以确定唾液检测的灵敏度。使用 MedCalc 计算检测 SARS-CoV-2 的灵敏度、特异性和阳性/阴性预测值（PPV、NPV）。
3018 名门诊患者（无症状：2683 名，有症状：335 名）经 qRT-PCR 检测，200 名阳性（男性：140 名，女性：60 名；年龄 37.9±12.8 岁；（81 名无症状，119 名有症状）。其中，128 名（64%）唾液阳性；81 名无症状患者中 39 名（47%），119 名有症状患者中 89 名（74.8%）。检测灵敏度为 60.9%（55.4-66.3%，95%CI），阴性预测值为 36%（32.9-39.2%，95%CI）。101 名住院患者（男性：65 名，女性：36 名；年龄 53.48±15.6 岁）中，以 HCWs 采集的 NPS 为对照，唾液检测灵敏度为 56.1%（47.5-64.5%，95%CI），特异性为 63.5%（50.4-75.3%，95%CI），PPV 为 77.2%，NPV 为 39.6%，自我采集拭子的灵敏度为 52.3%（44-60.5%，95%CI），特异性为 56.6%（42.3-70.2%，95%CI），PPV 为 77.2%，NPV 为 29.7%。与症状出现时间的阳性比较显示，在症状出现后第 3 天检测唾液的阳性率最高。此外，仅有 13 名（12.8%）住院患者的唾液呈阳性。
与鼻咽拭子相比，唾液更容易采集，是一种有前途的早期有症状患者检测 SARS-CoV-2 的方法。虽然目前不建议对无症状患者进行筛查，但优化采集和统一采样时间可能会提高灵敏度，使其能够作为社区层面的筛查工具。
