key: cord-0888611-f8nwq46h authors: Faíco-Filho, Klinger Soares; Júnior, Francisco Estivallet Finamor; Moreira, Luiz Vinícius Leão; Lins, Paulo Ricardo Gessolo; Justo, Alberto Fernando Oliveira; Bellei, Nancy title: Evaluation of the Panbio™ COVID-19 ag rapid test at an emergency room in a hospital in São Paulo, Brazil date: 2022-03-21 journal: Braz J Infect Dis DOI: 10.1016/j.bjid.2022.102349 sha: 8f340a50fa539f3817710a2b9c03b7b40dd88449 doc_id: 888611 cord_uid: f8nwq46h BACKGROUND: The performance characteristics of the Panbio™ COVID-19 Ag test was evaluated at an emergency room setting against RT-PCR, considered the gold-standard for the detection of SARS-CoV-2, in São Paulo, Brazil. The study aimed to determine the sensitivity, specificity, Positive Percent Agreement (PPA), and Negative Percent Agreement (NPA) as compared to RT-PCR. METHODS: Specimens from 127 suspected patients were tested by both the Panbio™ COVID-19 Ag test and by RT-PCR. RESULTS: In relation to RT-PCR using Ct values ≤ 40 as the upper limit for positivity, the Panbio™ COVID-19 Ag test showed an overall sensitivity of 84.3% (95% CI 75%‒93.8%) and 98.2% (95% CI 96%‒98.8%) overall specificity. For Ct values ≤ 25 (n = 37), the Panbio™ COVID-19 Ag test showed 97% sensitivity and a specificity of 73.3%. DISCUSSION: The concordance between the Panbio™ COVID-19 Ag test and RT-PCR was 97% at Ct values below 25 but decreased at higher Ct values. For disease control, it is very important to identify infected individuals who present COVID-19 symptoms and also those who are suspected of infection due to contact with infected individuals. CONCLUSION: The Panbio™ COVID-19 Ag test is suitable for use as a diagnostic test for rapid screening of patients presenting COVID-19 symptoms, or those suspected of being infected, prior to being admitted to hospital. Methods: Specimens from 127 suspected patients were tested by both the Panbio™ COVID-19 Ag test and by RT-PCR. Results: In relation to RT-PCR using Ct values ≤ 40 as the upper limit for positivity, the Panbio™ COVID-19 Ag test showed an overall sensitivity of 84.3% (95% CI 75%-93.8%) and 98.2% (95% CI 96%-98.8%) overall specificity. For Ct values ≤ 25 (n = 37), the Panbio™ COVID-19 Ag test showed 97% sensitivity and a specificity of 73.3%. The concordance between the Panbio™ COVID-19 Ag test and RT-PCR was 97% at Ct values below 25 but decreased at higher Ct values. For disease control, it is very important to identify infected individuals who present COVID-19 symptoms and also those who are suspected of infection due to contact with infected individuals. The Panbio™ COVID-19 Ag test is suitable for use as a diagnostic test for rapid screening of patients presenting COVID-19 symptoms, or those suspected of being infected, prior to being admitted to hospital. In late 2019, an outbreak of respiratory illness of unknown etiology was reported in Wuhan City, Hubei Province, China. The International Committee for Taxonomy of Viruses (ICTV) named the virus SARS-CoV-2 and is the cause of the global COVID-19 pandemic which, as of 18 th February 2022, has claimed more than 5.8 million lives (https://covid19.who.int/). The preferred diagnostic test for COVID-19 is Nucleic Acid Amplification Test (NAAT) using Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) performed in fluid from the nasal or nasopharyngeal cavities. The turn-around time can vary from same one day to one week. [1] [2] [3] Alternatively, a COVID-19 antigen test using nasal or nasopharyngeal samples can produce results in minutes. [3] A positive antigen test result is considered accurate, but low viral load in the sample can produce false-negative results. [5, 6] The Abbott Panbio™ COVID-19 Ag Rapid Test device is an in vitro rapid diagnostic test intended to aid in the diagnosis of COVID-19. The Panbio™ COVID-19 Ag Rapid Test device is a lateral flow immunochromatographic test used for the qualitative detection of SARS-CoV-2 antigens in human tissue fluids obtained from nasal or nasopharyngeal swabs. The Panbio™ COVID-19 Ag platform uses a cassette containing a lateral flow test strip and is intended for use by trained healthcare professionals in point-of-care and hospital settings. The product may be used in both laboratory and non-laboratory environments that meet the requirements specified in the product's Instructions For Use (IFU). The Panbio™ COVID-19 Ag test can be used for rapid screening in patients presenting COVID-19 symptoms, or in those who had contact with infected persons, prior to being admitted to hospital. In this study, the diagnostic performance, namely sensitivity, specificity, positive and negative predictive values, of the Panbio™ COVID-19 Ag Rapid test device using fluids obtained from nasopharyngeal swabs was assessed having RT-PCR test as gold-standard. This cross-sectional study was conducted at São Paulo Hospital, São Paulo, Brazil. Patients (≥18 years), treated at the emergency room and admitted for at least 24 hours were included if they met one of the following criteria: (1) symptoms suspected to be related to SARS-CoV-2 and/or contact with COVID-19 infected persons, (2) decompensation of underlying disease, or (3) suggestive tomographic alteration (ground glass opacities). Nasopharyngeal swab samples were simultaneously tested using the Panbio™ COVID-19 Ag test and inconclusive GeneFinder™ test results were tested using a second RT-PCR test -Mobius XGEN MASTER COVID-19 testtargeting the ORF1ab and N SARS-CoV-2 genes, per the IFU. [9] Test results for both RT-PCR methods were available within 6-24 hours. For this study, the performance of the Panbio™ COVID-19 Ag test was evaluated against the results of the gold standard test (RT-PCR). For RT-PCR, RNA was isolated from the subject's nasopharyngeal swab using the Quick-RNA Viral Kit (Zymo Research, Irvine, CA), according to the manufacturer's protocol. [10] After extraction, the RNA was used immediately, and the remaining RNA was stored at - In addition, 1 µL of an internal control was added to all the subjects' RNA samples. It is important to highlight that the content of the internal control is not described by the manufacturer. The plate was sealed and centrifuged, as described above. The thermal cycling conditions were as follows: (1) The agreement beyond chance between results of RT-PCR, defining positivity according to the above Ct cutoffs, and the Panbio TM COVID-19 Ag test was assessed by the kappa statistic. A total of 127 subjects were included. The median age was 63 years (22-69) and there were more males (54.3%) than females (vs. 45.7%). The characteristics of the study population are given in Table 1 . The Panbio TM COVID-19 Ag testing summary is shown in Table 2 . Table 3 provides details of the 10 samples that were negative by the Panbio TM COVID-19 Ag The red squares represent PCR-positive samples that were tested as negative by the Panbio TM COVID-19 Ag test. The highest viral loads were observed soon after symptom onset, which then gradually decreased but viral loads were very heterogeneous. This study was designed to evaluate the performance of the Panbio™ COVID-19 Ag test in comparison to RT-PCR, considered the gold-standard diagnostic test for COVID-19. The sensitivity was 84.3% (95% CI 75%-93.8%) and the specificity was 98.2% (95% CI 96%-98.8%), when the Ct cutoff used to define positivity was ≤40, similar to results seen in other recent studies. [11] [12] [13] [14] [15] In our study, the agreement beyond chance between the Panbio™ COVID-19 Ag test and RT-PCR decreases as Ct levels increase. In particular, the agreement was 78% for samples with Ct values of ≤ 25 but decreases at higher Cts. Additionally, sensitivity is not significantly different between subjects tested 0 to 11 days after symptom onset due to the high viral load observed in the patients even after 7 days. Following SARS-CoV-2 infection, the virus undergoes a period of incubation during with viral titers usually too low to detect, after which the virus undergoes exponential growth, leading to a peak in viral load and infectivity, followed by declining viral levels and clearance when infectivity is low. For disease control, it is very important to identify both infected individuals who present COVID-19 symptoms and also those who are suspected of infection due to contact with infected individuals. The Panbio™ COVID-19 Ag test has sufficient sensitivity and specificity to be used as a tool for the primary screening of such individuals. This is especially true in point-of-care and in patient settings where more elaborate laboratory facilities for RT-PCR are not available. Diagnostic testing for severe acute respiratory syndrome-related coronavirus-2. Annals of Internal Medicine Coronavirus Disease Comparison of molecular testing strategies for COVID-19 control: a mathematical modelling study Diagnostic strategies for SARS-CoV-2 infection and interpretation of microbiological results World Health Organization. COVID-19 Target product profiles for priority diagnostics to support response to the COVID-19 Panbio TM COVID-19 Ag Instructions For Use. 41FK10-07-AO GeneFinder™ COVID-19 Plus RealAmp Kit Instructions For Use. IFMR-45 Mobius XGEN MASTER COVID-19 Test Instructions For Use Zymo Quick-RNA™ Viral Kit Instruction Manual Real-life validation of the Panbio™ COVID-19 antigen rapid test (Abbott) in community-dwelling subjects with symptoms of potential SARS-CoV-2 infection Field evaluation of a rapid antigen test (Panbio™ COVID-19 Ag Rapid Test Device) for COVID-19 diagnosis in primary healthcare centres Viral dynamics and realtime RT-PCR Ct values correlation with disease severity in COVID-19 Field evaluation of a rapid antigen test (Panbio™ COVID-19 Ag Rapid Test Device) for COVID-19 diagnosis in primary healthcare centres Real-life validation of the Panbio™ COVID-19 antigen rapid test (Abbott) in community-dwelling subjects with symptoms of potential SARS-CoV-2 infection The authors declare no conflicts of interest.