Oral saliva swab reverse transcription PCR for Covid-19 in the paediatric population.

OBJECTIVES: To evaluate the performance of oral saliva swab (OSS) reverse transcription PCR (RT-PCR) compared with RT-PCR and antigen rapid diagnostic test (Ag-RDT) on nasopharyngeal swabs (NPS) for SARS-CoV-2 in children. DESIGN: Cross-sectional multicentre diagnostic study. SETTING: Study nested in a prospective, observational cohort (EPICO-AEP) performed between February and March 2021 including 10 hospitals in Spain. PATIENTS: Children from 0 to 18 years with symptoms compatible with Covid-19 of ≤5 days of duration were included. Two NPS samples (Ag-RDT and RT-PCR) and one OSS sample for RT-PCR were collected. MAIN OUTCOME: Performance of Ag-RDT and RT-PCR on NPS and RT-PCR on OSS sample for SARS-CoV-2. RESULTS: 1174 children were included, aged 3.8 years (IQR 1.7-9.0); 73/1174 (6.2%) patients tested positive by at least one of the techniques. Sensitivity and specificity of OSS RT-PCR were 72.1% (95% CI 59.7 to 81.9) and 99.6% (95% CI 99 to 99.9), respectively, versus 61.8% (95% CI 49.1 to 73) and 99.9% (95% CI 99.4 to 100) for the Ag-RDT. Kappa index was 0.79 (95% CI 0.72 to 0.88) for OSS RT-PCR and 0.74 (95% CI 0.65 to 0.84) for Ag-RDT versus NPS RT-PCR. CONCLUSIONS: RT-PCR on the OSS sample is an accurate option for SARS-CoV-2 testing in children. A less intrusive technique for younger patients, who usually are tested frequently, might increase the number of patients tested.

Clinitest rapid COVID-19 antigen test for the diagnosis of SARS-CoV-2 infection: A multicenter evaluation study.

OBJECTIVES: RT-PCR assay is the reference method for diagnosis of COVID-19, but it is also a laborious and time-consuming technic, limiting the availability of testing. Rapid antigen-detection tests are faster and less expensive; however, the reliability of these tests must be validated before they can be used widely. The objective of this study was to determine the performance of the Clinitest Rapid COVID-19 Antigen Test (ClinitestRT) (SIEMENS) for SARS-CoV-2 in nasopharyngeal swab specimens. METHODS: This prospective multicenter study was carried out in three Spanish university hospitals including individuals with clinical symptoms or epidemiological criteria for COVID-19. Only individuals with ≤7 days from the onset of symptoms or from exposure to a confirmed case of COVID-19 were included. Two nasopharyngeal samples were taken to perform the ClinitestRT, as a point-of-care test, and a diagnostic RT-PCR test. RESULTS: Overall sensitivity and specificity for the ClinitestRT among the 450 patients studied were 93.3% (CI 95%: 89.7-96.8) and 99.2% (CI 95%: 97.2-99.8), respectively. Sensitivity in participants with ≤5 days of the clinical course was 93.6% (CI 95%: 89.2-96.3), and in participants who had a CT < 25 for the RT-PCR test was 98.4% (CI 95%: 94.5-99.6). Agreement between techniques was 96.7% (kappa score: 0.93; CI 95%: 0.90-0.97). CONCLUSIONS: The ClinitestRT provides good clinical performance, with more reliable results for patients with a higher viral load. The results must be interpreted based on the local epidemiological context.

Think of the Children: Evaluation of SARS-CoV-2 Rapid Antigen Test in Pediatric Population.

BACKGROUND: Real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is the reference laboratory method to diagnose SARS-CoV-2 infection then requires equipment and is time-consuming. There is a crucial demand for rapid techniques such as antigen detection test. Considering the different diagnostic accuracy of tests with other respiratory viruses in adults and children, SARS-CoV-2 antigen test must be evaluated specifically in children. METHODS: The purpose of this study was to evaluate the performance of Panbio COVID-19 Ag Rapid Test Device (Abbott) as a point-of-care test for diagnosis of SARS-CoV-2 in comparison to RT-qPCR in a pediatric population. RESULTS: Four hundred forty nasopharyngeal swabs were tested. Amongst the 18 positive RT-qPCR samples, 14 were detected by the rapid antigen test, given an overall sensitivity of 77.7%. All the samples detected positive with the antigen rapid test were also positive with RT-qPCR. CONCLUSION: The sensitivity of Panbio COVID-19 Ag Rapid Test Device is lower in children than in adults. Nevertheless, considering the good values of specificity, negative and positive predictive values this test could be used as a frontline test to obtain quick results, although the negative values with COVID-19 high clinical suspicion should be confirmed using RT-qPCR.

Evaluation of three immunochromatographic tests for rapid detection of antibodies against SARS-CoV-2.

Lateral flow immunoassays (LFIA) for rapid detection of specific antibodies (IgM and IgG) against SARS-CoV-2 in different human specimens have been developed in response to the pandemic. The aim of this study is to evaluate three immunocromathographic assays (Sienna®, Wondfo® and Prometheus®) for detection of antibodies against SARS-CoV-2 in serum samples, considering RT-qPCR as a reference. A total of 145 serum samples from 145 patients with clinical suspicion of COVID-19 were collected: all of the samples were tested with Sienna®, 117 with Wondfo® and 89 with Prometheus®. The overall results of sensitivity, specificity, positive predictive value and negative predictive value obtained were as follows: 64.4%, 75%, 85.5% and 47.8% with Sienna®; 45.2%, 81.8%, 80.5% and 47.4% with Wondfo® and 75.5%, 12.5%, 51.4% and 29.4% with Prometheus®. The accuracy of the test for Sienna®, Wondfo® and Prometheus® was 67.6%, 59% and 47.2%, with a prevalence of COVID-19 of 69.7%, 62.4% and 55.1% respectively. Sensitivity of the three tests (Sienna®, Wondfo® and Prometheus® respectively) along the three different stages was 36.6%, 18.8% and 68.6% in the early stage (first week); 81.3%, 74.1% and 90.9% in the intermediate stage (second week) and 100%, 83.3% and 100% in the late stage (third week). The results demonstrate that even though Prometheus® presented a high sensitivity, the specificity was notably lower than the other two tests. Sienna® showed the greatest contrast between sensitivity and specificity, achieving the best accuracy, followed by Wondfo®. The sensitivity of the three ICT assays was higher in late stages of the disease.