A Direct Comparison of Enhanced Saliva to Nasopharyngeal Swab for the Detection of SARS-CoV-2 in Symptomatic Patients.

The ongoing coronavirus disease 2019 (COVID-19) pandemic has resulted in shortages of nasopharyngeal swabs (NPS) and viral transport media, necessitating the search for alternate diagnostic specimens, such as saliva. We directly compared matched saliva and NPS specimens from symptomatic patients suspected of having COVID-19. An enhanced saliva specimen (i.e., strong sniff, elicited cough, and collection of saliva/secretions) was collected without transport medium prior to collection of NPS from 224 patients with symptoms deemed consistent with COVID-19. Both specimens were tested with the CDC 2019 nCoV real-time RT-PCR diagnostic panel (4 February 2020 version), with the NPS result used as the reference standard. For the 216 patients included in the final analysis, there was 100% positive agreement (38/38 positive specimens) and 99.4% negative agreement (177/178 negative specimens). The one discrepant specimen had the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) confirmed in the saliva specimen using an alternate FDA EUA assay. The overall mean difference in cycle threshold (CT ) values for the positive NPS and saliva specimens was -3.61 (95% confidence interval [CI], -5.78 to -1.44; P = 0.002). An enhanced saliva specimen performed as well as NPS for the qualitative detection of SARS-CoV-2 in symptomatic patients, although the overall mean viral load in saliva was lower.

Procop GW ，Shrestha NK ，Vogel S ，Van Sickle K ，Harrington S ，Rhoads DD ，Rubin BP ，Terpeluk P ... -  《-》

Self-Collected Anterior Nasal and Saliva Specimens versus Health Care Worker-Collected Nasopharyngeal Swabs for the Molecular Detection of SARS-CoV-2.

We prospectively compared health care worker-collected nasopharyngeal swabs (NPS) to self-collected anterior nasal swabs (ANS) and straight saliva for the diagnosis of coronavirus disease 2019 (COVID-19) in 354 patients. The percent positive agreement between NPS and ANS or saliva was 86.3% (95% confidence interval [CI], 76.7 to 92.9%) and 93.8% (95% CI, 86.0 to 97.9%), respectively. The percent negative agreement was 99.6% (95% CI, 98.0 to 100.0%) for NPS versus ANS and 97.8% (95% CI, 95.3 to 99.2%) for NPS versus saliva. More cases were detected by the use of NPS (n = 80) and saliva (n = 81) than by the use of ANS (n = 70), but no single specimen type detected all severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections.

Hanson KE ，Barker AP ，Hillyard DR ，Gilmore N ，Barrett JW ，Orlandi RR ，Shakir SM ... -  《-》

Comparative evaluation of nasopharyngeal swab and saliva specimens for the molecular detection of SARS-CoV-2 RNA in Japanese patients with COVID-19.

Considering the issues of shortage of medical resources and the invasiveness and infection risk involved in the collection of nasopharyngeal swab specimens, there is a need for an effective alternative test specimen for SARS-CoV-2 RNA detection. Here, we investigated suitability of saliva as a non-invasively obtained specimen for molecular detection of SARS-CoV-2 RNA in Japanese patients with COVID-19. In total, 28 paired clinical specimens of saliva and nasopharyngeal swabs were collected from 12 patients at various time points after symptom onset. Each specimen was assayed using reverse transcription real-time polymerase chain reaction (rRT-PCR) on the BD MAX open system using primers and probes targeting the N-gene. The saliva and nasopharyngeal swab specimens showed 19 and 15 positive results, respectively. No invalid (PCR inhibition) result was observed for any specimen. The qualitative results of each specimen obtained in the period immediately after symptom onset were similar. Three convalescent patients presented saliva-positive results, whereas their nasopharyngeal swabs were negative at four different time points, suggesting that saliva may be superior to nasopharyngeal swabs in terms of obtaining stable assay result of SARS-CoV-2. In conclusion, our results suggest that saliva can potentially serve as an alternative to nasopharyngeal swabs as a specimen for SARS-CoV-2 rRT-PCR. As saliva can be collected by patients themselves, it may be an effective way to overcome the shortage of personal protective equipment and specimen sampling tools.

Sakanashi D ，Asai N ，Nakamura A ，Miyazaki N ，Kawamoto Y ，Ohno T ，Yamada A ，Koita I ，Suematsu H ，Hagihara M ，Shiota A ，Kurumiya A ，Sakata M ，Kato S ，Muramatsu Y ，Koizumi Y ，Kishino T ，Ohashi W ，Yamagishi Y ，Mikamo H ... -  《-》

Evaluation of simple nucleic acid extraction methods for the detection of SARS-CoV-2 in nasopharyngeal and saliva specimens during global shortage of extraction kits.

The severe shortage of nucleic acid extraction kits during the current COVID-19 pandemic represents a key limiting factor in testing capacity. This study compared the results of SARS-CoV-2 RT-PCR using different simple nucleic acid extraction methods on nasopharyngeal and saliva specimens. Fifty nasopharyngeal swab and saliva specimens previously tested positive for SARS-CoV-2 were retrieved. Three different methods of nucleic acid extraction were compared. The first method involves incubating the specimen with proteinase K, and then heat treatment at 98 °C for 5 min (PKH); the second method involves heat treatment at 98 °C for 5 min without proteinase K pre-incubation (heat only); the third method involves no pre-processing steps (direct). The products from all 3 methods were tested by SARS-CoV-2 RT-PCR. PKH had significantly higher positive rate in SARS-CoV-2 RT-PCR (80 %) than those of heat only (58 %; P = 0.001) or direct (56 %; P = 0.002). The median Ct value was significantly earlier for PKH (median Ct: 37.0, IQR 31.7-40) than that of heat only (median Ct: 40, IQR 36.2-41; P < 0.0001) and direct (median Ct, 37.5; IQR 33.9-41.0; P = 0.0049). Subgroup analysis showed that PKH had higher detection rate, lower limit of detection and earlier Ct values than the other two groups for both NPS and saliva specimens. PKH pre-processing resulted in the highest detection rate of SARS-CoV-2 by RT-PCR, and represents an alternative method for nucleic acid extraction when commercial extraction kits are not available.

Chu AW ，Chan WM ，Ip JD ，Yip CC ，Chan JF ，Yuen KY ，To KK ... -  《-》

Viral Load Kinetics of SARS-CoV-2 Infection in Saliva in Korean Patients: a Prospective Multi-center Comparative Study.

This study was performed to compare the viral load and kinetics of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in saliva with those in standard nasopharyngeal/oropharyngeal (NP/OP) swabs. Fifteen patients with SARS-CoV-2 infection from four hospitals were prospectively enrolled and matched samples of nasopharyngeal/oropharyngeal swabs and saliva were collected at Day 1 of admission and every other day till consequently negative for two times. Real-time reverse transcription polymerase chain reaction (rRT-PCR) was performed to detect the envelope (E) and RNA-dependent RNA polymerase (RdRP) genes. The cycle threshold values of saliva were comparable to those of NP/OP swabs overall (P = 0.720, Mann-Whitney U test). However, the overall sensitivity of rRT-PCR using saliva was 64% (34/53), which is lower than the 77% (41/53) using NP/OP swabs. The sensitivity of rRT-PCR using saliva was especially lower in early stage of symptom onset (1-5 days; 8/15; 53%) and in patients who did not have sputum (12/22; 55%). Saliva sample itself is not appropriate for initial diagnosis of coronavirus disease 2019 (COVID-19) to replace NP/OP swabs, especially for the person who does not produce sputum. COVID-19 cannot be excluded when the test using saliva is negative, and it is necessary to retest using NP/OP swabs.

Kim SE ，Lee JY ，Lee A ，Kim S ，Park KH ，Jung SI ，Kang SJ ，Oh TH ，Kim UJ ，Lee SY ，Kee SJ ，Jang HC ... -  《-》