Sensitivity Of Nasopharyngeal Swab Research Articles

Sensitivity of nasopharyngeal swab and saliva specimens in the detection of SARS-CoV-2 virus among boarding school girls

With the reopening of schools, the detection of coronavirus disease 2019 (COVID-19) in children is very important in order to prevent outbreaks in schools and to reduce the risk of more severe post-COVID-19 complications. Various specimens can be used to detect the SARS-CoV-2 virus, and saliva has been considered as an alternative specimen in adults. However, data in children are lacking, especially among the female population. This study compared the efficacy of saliva specimens with nasopharyngeal swab specimens for the detection of severe acute respiratory syndrome coronavirus-2 using reverse transcriptase polymerase chain reaction. This study evaluated the diagnostic performance of saliva among boarding school girls at three time points: diagnosis, and days 7 and 14 since first confirmation using a nasopharyngeal swab specimen. Eighty-four paired samples from 36 individuals were compared. Nasopharyngeal samplings were carried out by trained health officers, while saliva samplings were performed independently by children. The overall percentage agreement (OPA) between saliva and nasopharyngeal swabs was 50.2%. The OPA was 52.8% at diagnosis, and this increased slightly to 54.2% at day 7, and subsequently decreased to 45.8% at day 14. Saliva specimens had sensitivity of 44.6%, specificity of 80.0%, positive predictive value of 94.2% and negative predictive value of 16.3% compared with nasopharyngeal swab specimens for the diagnosis of COVID-19. The use of saliva as an alternative specimen for the diagnosis of COVID-19 in children should be considered carefully. Thorough sampling instructions should be given in order to minimize bias in the findings.

Sensitivity of SARS-CoV-2 Detection With Nasopharyngeal Swabs.

Background: SARS-CoV-2-infected subjects have been proven contagious in the symptomatic, pre-symptomatic and asymptomatic phase. The identification of these patients is crucial in order to prevent virus circulation. No reliable data on the sensitivity of nasopharyngeal swabs (NPS) are available because of the lack of a shared reference standard to identify SARS-CoV-2 infected patients. The aim of our study was to collect data on patients with a known diagnosis of COVID-19 who underwent serial testing to assess NPS sensitivity.Methods: The study was a multi-center, observational, retrospective clinical study with consecutive enrollment. We enrolled patients who met all of the following inclusion criteria: clinical recovery, documented SARS-CoV-2 infection (≥1 positive rRT-PCR result) and ≥1 positive NPS among the first two follow-up swabs. A positive NPS not preceded by a negative nasopharyngeal swab collected 24–48 h earlier was considered a true positive. A negative NPS followed by a positive NPS collected 24–48 h later was regarded as a false negative. The primary outcome was to define sensitivity of SARS-CoV-2 detection with NPS.Results: Three hundred and ninety three NPS were evaluated in 233 patients; the sensitivity was 77% (95% CI, 73 to 81%). Sensitivity of the first follow-up NPS (n = 233) was 79% (95% CI, 73 to 84%) with no significant variations over time. We found no statistically significant differences in the sensitivity of the first follow-up NPS according to time since symptom onset, age, sex, number of comorbidities, and onset symptoms.Conclusions: NPS utility in the diagnostic algorithm of COVID-19 should be reconsidered.

Seroprevalence of SARS-Cov-2 in the setting of a non-dedicated COVID-19 hospital in a low CoV-2 incidence area: Implications for surgery

The aim of this study was to assess the seroprevalence of SARS-Cov-2 in the setting of a non-dedicated COVID-19 hospital in a low CoV-2 incidence area. We analysed the data of the patients admitted at our surgical department during the period 31st March - June 30, 2020. Among 86 patients included in the study, we found 2 (2.3%) patients positive for both SARS-CoV-2 specific IgM and IgG, 2 (2.3%) for only SARS-CoV-2 specific IgM, and 1 for only SARS-CoV-2 specific IgG. Thus, seroprevalence for SARS-CoV-2 was 5.8%; nasopharyngeal swab was negative in all the cases. Considering the current limitations in sensitivity of nasopharyngeal swab, the uncertainty in the natural history of SARS-CoV2, and the reported prevalence of CoV-2, we think that careful preadmission triage and tests, the use of personal protective equipment and safe management of surgical smoke are mandatory also in our context of low CoV-2 incidence area.

Nasopharyngeal Swabs Are More Sensitive Than Oropharyngeal Swabs for COVID-19 Diagnosis and Monitoring the SARS-CoV-2 Load.

Objective: Detection of SARS-CoV-2 by oropharyngeal swabs (OPS) and nasopharyngeal swabs (NPS) is an essential method for coronavirus disease 2019 (COVID-19) management. It is not clear how detection rate, sensitivity, and the risk of exposure for medical providers differ in two sampling methods.Methods: In this prospective study, 120 paired NPS and OPS specimens were collected from 120 inpatients with confirmed COVID-19. SARS-CoV-2 nucleic acid in swabs were detected by real-time RT-PCR. The SARS-CoV-2 detection rate, sensitivity, and viral load were analyzed with regards NPS and OPS. Sampling discomfort reported by patients was evaluated.Results: The SARS-CoV-2 detection rate was significantly higher for NPS [46.7% (56/120)] than OPS [10.0% (12/120)] (P < 0.001). The sensitivity of NPS was also significantly higher than that of OPS (P < 0.001). At the time of sampling, the time of detectable SARS-CoV-2 had a longer median duration (25.0 vs. 20.5 days, respectively) and a longer maximum duration (41 vs. 39 days, respectively) in NPS than OPS. The mean cycle threshold (Ct) value of NPS (37.8, 95% CI: 37.0–38.6) was significantly lower than that of OPS (39.4, 95% CI: 38.9–39.8) by 1.6 (95% CI 1.0–2.2, P < 0.001), indicating that the SARS-CoV-2 load was significantly higher in NPS specimens than OPS. Patient discomfort was low in both sampling methods. During NPS sampling, patients were significantly less likely to have nausea and vomit.Conclusions: NPS had significantly higher SARS-CoV-2 detection rate, sensitivity, and viral load than OPS. NPS could reduce droplets production during swabs. NPS should be recommended for diagnosing COVID-19 and monitoring SARS-CoV-2 load.Chinese Clinical Trial Registry, number: ChiCTR2000029883.

Comparison among nasopharyngeal swab, nasal wash, and oropharyngeal swab for respiratory virus detection in adults with acute pharyngitis

BackgroundAcute pharyngitis is frequently seen in primary care. Acute viral pharyngitis may be easily misdiagnosed as acute bacterial pharyngitis. Laboratory-confirmed diagnosis of respiratory viruses is recommended. The purpose of this study was to compare the sensitivities among oropharyngeal swab (OPS), nasopharyngeal swab (NPS), and nasal wash (NW) in adults with acute pharyngitis.MethodsOPS, NPS, and NW were obtained from each participant with acute pharyngitis. The specimens were tested for 15 respiratory viruses by TaqMan real-time polymerase chain reaction. A sample was considered to be a true positive if any of the specimens was positive. The sensitivities among samples were compared by chi-square test or Fisher’s exact test, as appropriate.ResultsOne hundred three triple samples collected consecutively by OPS, NPS, and NW were obtained. In 73 patients, one or more viruses were detected by any of the three methods. Among all viruses, the sensitivity of NPS was significantly higher than that of NW (74% vs. 49%, respectively; p < 0.01) and OPS (74% vs. 49%, respectively; p < 0.01).ConclusionsFlocked NPS collection may be the most effective alternative to NW and OPS for detection of respiratory viruses in adults with acute pharyngitis using TaqMan real-time polymerase chain reaction.