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1.
Indian J Med Res ; 155(1): 86-90, 2022 01.
Article in English | MEDLINE | ID: covidwho-2201765

ABSTRACT

To implement the strategy of test, track and treat to tackle the ongoing COVID-19 pandemic, the number of real-time RT-PCR-based testing laboratories was increased for diagnosis of SARS-CoV-2 in the country. To ensure reliability of the laboratory results, the Indian Council of Medical Research initiated external quality assessment (EQA) by deploying inter-laboratory quality control (ILQC) activity for these laboratories by nominating 34 quality control (QC) laboratories. This report presents the results of this activity for a period of September 2020 till November 2020. A total of 597 laboratories participated in this activity and 86 per cent of these scored ≥90 per cent concordance with QC laboratories. This ILQC activity showcased India's preparedness in quality diagnosis of SARS-CoV-2.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , COVID-19 Testing , Clinical Laboratory Techniques/methods , Humans , Pandemics , Reproducibility of Results , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/genetics
2.
Microbiol Spectr ; 10(1): e0245521, 2022 02 23.
Article in English | MEDLINE | ID: covidwho-2193554

ABSTRACT

Containment measures employed during the COVID-19 pandemic included prompt recognition of cases, isolation, and contact tracing. Bilateral nasal (NA) swabs applied to a commercial antigen-based rapid diagnostic test (Ag-RDT) offer a simpler and more comfortable alternative to nasopharyngeal (NP) collection; however, little is known about the sensitivity of this method in an asymptomatic population. Participants in community-based asymptomatic testing sites were screened for SARS-CoV-2 using an Ag-RDT with NP sampling. Positive individuals returned for confirmatory molecular testing and consented to repeating the Ag-RDT using a bilateral NA swab for comparison. Residual test buffer (RTB) from Ag-RDTs was subjected to real-time reverse transcription-PCR (RT-PCR). Of 123,617 asymptomatic individuals, 197 NP Ag-RDT-positive participants were included, with 175 confirmed positive by RT-PCR. Of these cases, 154 were identified from the NA swab collection with Ag-RDT, with a sensitivity of 88.0% compared to the NP swab collection. Stratifying results by RT-PCR cycle threshold demonstrated that sensitivity of the nasal collection method varied based on the cycle threshold (CT) value of the paired RT-PCR sample. RT-PCR testing on the RTB from the Ag-RDT using NP and NA swab collections resulted in 100.0% and 98.7% sensitivity, respectively. NA swabs provide an adequate alternative to NP swab collection for use with Ag-RDT, with the recognition that the test is most sensitive in specimens with high viral loads. With the high sensitivity of RT-PCR testing on RTB from Ag-RDT, a more streamlined approach to confirmatory testing is possible without recollection or use of paired collections strategies. IMPORTANCE Nasal swabbing for SARS-CoV-2 (COVID-19) comes with many benefits but is slightly less sensitive than traditional nasopharyngeal swabbing; however, confirmatory lab-based testing could be performed directly from the residual buffer from either sample type.


Subject(s)
Antigens, Viral/analysis , COVID-19/virology , Carrier State/virology , Nasopharynx/virology , Nose/virology , SARS-CoV-2/isolation & purification , Specimen Handling/methods , Antigens, Viral/genetics , Antigens, Viral/immunology , Asymptomatic Diseases , COVID-19/diagnosis , COVID-19 Serological Testing , Humans , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/classification , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Sensitivity and Specificity
3.
Infect Dis Now ; 52(8): 453-455, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2179305

ABSTRACT

Real-time PCR plays a key role in the diagnosis of viral infections. Multiple kits can detect or quantify genomes of various viruses with the same thermocycling program. Detection of RNA viruses includes an additional step of reverse transcription and challenge their detection in a single run with DNA viruses. We investigated the analytical performance of HSV-1, HSV-2 and VZV DNA quantification with Altona RealStar® PCR kits using the RT-PCR program for RNA viruses instead of the PCR program for DNA viruses. For each three viruses, Bland-Altman distribution did not show differences between both programs, and quantification curves generated with both thermocycling programs confirmed high correlation (R2 ≥ 0.9983). Detection of low viral load samples was evaluated, on 10-times repeat-test. All replicate samples were detected with both thermocycling programs and were quantified at similar viral loads (bias in log10 copies/mL: +0.05 (HSV-1), -0.01 (HSV-2) and +0.25 (VZV)). This confirms the feasibility of using the RT-PCR thermocycling program to detect and quantify the genome of RNA and DNA viruses in a single run.


Subject(s)
RNA Viruses , Humans , Reverse Transcriptase Polymerase Chain Reaction , Sensitivity and Specificity , Real-Time Polymerase Chain Reaction , DNA Viruses
5.
Front Cell Infect Microbiol ; 12: 960065, 2022.
Article in English | MEDLINE | ID: covidwho-2141708

ABSTRACT

Known SARS-CoV-2 variants of concern (VOCs) can be detected and differentiated using an RT-PCR-based genotyping approach, which offers quicker time to result, lower cost, higher flexibility, and use of the same laboratory instrumentation for detection of SARS-CoV-2 when compared with whole genome sequencing (WGS). In the current study, we demonstrate how we applied a genotyping approach for identification of all VOCs and that such technique can offer comparable performance to WGS for identification of known SARS-CoV-2 VOCs, including more recent strains, Omicron BA.1 and BA.2.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/genetics , Genotype , Whole Genome Sequencing
6.
PLoS One ; 17(10): e0268160, 2022.
Article in English | MEDLINE | ID: covidwho-2140397

ABSTRACT

BACKGROUND: Rapid diagnostics are vital for curving the transmission and control of the COVID-19 pandemic. Although many commercially available antigen-based rapid diagnostic tests (Ag-RDTs) for the detection of SARS-CoV-2 are recommended by the WHO, their diagnostic performance has not yet been assessed in Ethiopia. So far, the vast majority of studies assessing diagnostic accuracies of rapid antigen tests considered RT-PCR as a reference standard, which inevitably leads to bias when RT-PCR is not 100% sensitive and specific. Thus, this study aimed to evaluate the diagnostic performance of Panbio™ jointly with the RT-PCR for the detection of SARS-CoV-2. METHODS: A prospective cross-sectional study was done from July to September 2021 in Addis Ababa, Ethiopia, during the third wave of the pandemic involving two health centers and two hospitals. Diagnostic sensitivity and specificity of Panbio™ and RT-PCR were obtained using Bayesian Latent-Class Models (BLCM). RESULTS: 438 COVID-19 presumptive clients were enrolled, 239 (54.6%) were females, of whom 196 (44.7%) had a positive RT-PCR and 158 (36.1%) were Panbio™ positive. The Panbio™ and RT-PCR had a sensitivity (95% CrI) of 99.6 (98.4-100) %, 89.3 (83.2-97.6) % and specificity (95% CrI) of 93.4 (82.3-100) %, and 99.1 (97.5-100) %, respectively. Most of the study participants, 318 (72.6%) exhibited COVID-19 symptoms; the most reported was cough 191 (43.6%). CONCLUSION: As expected the RT-PCR performed very well with a near-perfect specificity and a high, but not perfect sensitivity. The diagnostic performance of Panbio™ is coherent with the WHO established criteria of having a sensitivity ≥80% for Ag-RDTs. Both tests displayed high diagnostic accuracies in patients with and without symptoms. Hence, we recommend the use of the Panbio™ for both symptomatic and asymptomatic individuals in clinical settings for screening purposes.


Subject(s)
COVID-19 , SARS-CoV-2 , Female , Humans , Male , SARS-CoV-2/genetics , COVID-19/diagnosis , COVID-19/epidemiology , Reverse Transcriptase Polymerase Chain Reaction , Pandemics , Cross-Sectional Studies , Ethiopia/epidemiology , Bayes Theorem , Prospective Studies , Sensitivity and Specificity , Antigens, Viral/analysis
7.
Clin Lab Med ; 42(2): 237-248, 2022 06.
Article in English | MEDLINE | ID: covidwho-2130431

ABSTRACT

Reverse transcription-polymerase chain reaction (RT-PCR) tests for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), are approved for qualitative use. The cycle threshold (Ct) value reflects the concentration of viral RNA in the sample, with lower Ct values indicating higher levels of RNA. Caregivers may wish to use the Ct value to determine the progression of infection, how severe the infection will be, and whether the patient can transmit the virus. Variability of Ct values and the data supporting these uses should be considered when deciding whether and how to use Ct values in clinical care.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , Humans , RNA, Viral/analysis , RNA, Viral/genetics , Reverse Transcriptase Polymerase Chain Reaction , Reverse Transcription , SARS-CoV-2/genetics
8.
Klin Lab Diagn ; 67(11): 672-677, 2022 Nov 14.
Article in English | MEDLINE | ID: covidwho-2146783

ABSTRACT

COVID-19 is a disease caused by the new coronavirus SARS-CoV-2. Outbreaks were first reported in China on December 31, 2019. Exactly one month later, the WHO declared the outbreak a public health emergency of international concern, and on March 11, it was declared a pandemic. In February, the infection began to spread rapidly to various countries, with Europe declared the center. By April 17, 2020, cases had been confirmed in all subjects of the Russian Federation. At the beginning of September 2020, the number of cases exceeded one million; at November 19, two million; at December 26, three million. At February 10, 2021, four million; at May 23, five million; at July 20, six million; at September 5, seven million; at October 18, eight million; at November 13, nine million; and at December 12, 2021, ten million. The rapid spread of the virus, accompanied by a significant increase in the number of infections and deaths. A total of about 18.6 million cases were recorded at the end of the first half of 2022. The total number of deaths from coronavirus in Russia at that time was 382,313 (2.06% of all cases). The number of tests performed by various analytical methods amounted to over 274, 5 million, i.e. 1.9 million per 1 million population. The rapid spread and the increase in new infections caused by SARS-CoV-2 made it necessary to use new epidemiological and diagnostic approaches based on fast, accurate and reliable technology for detecting the infectious agent. One such virus detection method is polymerase chain reaction with reverse transcription and real-time detection of the results. The review presents the domestic market offerings of PCR diagnostic kits and provides their comparative consumer characteristics.


Subject(s)
COVID-19 , Reverse Transcription , Humans , COVID-19/diagnosis , COVID-19/epidemiology , SARS-CoV-2/genetics , Reverse Transcriptase Polymerase Chain Reaction , Real-Time Polymerase Chain Reaction
9.
Klin Lab Diagn ; 67(11): 663-667, 2022 Nov 14.
Article in English | MEDLINE | ID: covidwho-2146780

ABSTRACT

The coronavirus infection continues to spread around the world. In this regard, the purpose of this work was: to develop a set of reagents for the qualitative detection of SARS-CoV-2 virus RNA. The set was developed by CJSC «Ecolab¼, 20 positive samples were used to develop the kit. The research method consisted of several stages: isolation of SARS-CoV-2 RNA, RNA reverse transcription reaction and PCR amplification of cDNA with simultaneous detection of the result in real time. The main characteristics of the kit: analytical sensitivity - 100%, specificity - 100%, accuracy - 100%. Thus, our method for diagnosing a new coronavirus infection based on real-time RT-PCR makes it possible to qualitatively and quickly detect betacoronavirus RNA in clinical material from patients and healthy individuals with suspected coronavirus infection and other symptoms of SARS.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/genetics , RNA, Viral/analysis , Indicators and Reagents , Sensitivity and Specificity , COVID-19/diagnosis , Real-Time Polymerase Chain Reaction
10.
Ann Intern Med ; 173(7): 536-541, 2020 10 06.
Article in English | MEDLINE | ID: covidwho-2110869

ABSTRACT

BACKGROUND: The incidence and severity of coronavirus disease 2019 (COVID-19) among HIV-positive persons receiving antiretroviral therapy (ART) have not been characterized in large populations. OBJECTIVE: To describe the incidence and severity of COVID-19 by nucleos(t)ide reverse transcriptase inhibitor (NRTI) use among HIV-positive persons receiving ART. DESIGN: Cohort study. SETTING: HIV clinics in 60 Spanish hospitals between 1 February and 15 April 2020. PARTICIPANTS: 77 590 HIV-positive persons receiving ART. MEASUREMENTS: Estimated risks (cumulative incidences) per 10 000 persons and 95% CIs for polymerase chain reaction-confirmed COVID-19 diagnosis, hospitalization, intensive care unit (ICU) admission, and death. Risk and 95% CIs for COVID-19 diagnosis and hospital admission by use of the NRTIs tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC), tenofovir alafenamide (TAF)/FTC, abacavir (ABC)/lamivudine (3TC), and others were estimated through Poisson regression models. RESULTS: Of 77 590 HIV-positive persons receiving ART, 236 were diagnosed with COVID-19, 151 were hospitalized, 15 were admitted to the ICU, and 20 died. The risks for COVID-19 diagnosis and hospitalization were greater in men and persons older than 70 years. The risk for COVID-19 hospitalization was 20.3 (95% CI, 15.2 to 26.7) among patients receiving TAF/FTC, 10.5 (CI, 5.6 to 17.9) among those receiving TDF/FTC, 23.4 (CI, 17.2 to 31.1) among those receiving ABC/3TC, and 20.0 (CI, 14.2 to 27.3) for those receiving other regimens. The corresponding risks for COVID-19 diagnosis were 39.1 (CI, 31.8 to 47.6), 16.9 (CI, 10.5 to 25.9), 28.3 (CI, 21.5 to 36.7), and 29.7 (CI, 22.6 to 38.4), respectively. No patient receiving TDF/FTC was admitted to the ICU or died. LIMITATION: Residual confounding by comorbid conditions cannot be completely excluded. CONCLUSION: HIV-positive patients receiving TDF/FTC have a lower risk for COVID-19 and related hospitalization than those receiving other therapies. These findings warrant further investigation in HIV preexposure prophylaxis studies and randomized trials in persons without HIV. PRIMARY FUNDING SOURCE: Instituto de Salud Carlos III and National Institutes of Health.


Subject(s)
Antiretroviral Therapy, Highly Active , Coronavirus Infections/epidemiology , HIV Infections/drug therapy , Pneumonia, Viral/epidemiology , Adenine/analogs & derivatives , Adult , Aged , Betacoronavirus , COVID-19 , Coronavirus Infections/mortality , Dideoxynucleosides , Drug Combinations , Emtricitabine , Female , HIV Infections/mortality , Hospitalization/statistics & numerical data , Humans , Incidence , Intensive Care Units/statistics & numerical data , Lamivudine , Male , Middle Aged , Pandemics , Pneumonia, Viral/mortality , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2 , Severity of Illness Index , Spain/epidemiology , Tenofovir
11.
Anal Chem ; 94(47): 16361-16368, 2022 Nov 29.
Article in English | MEDLINE | ID: covidwho-2119248

ABSTRACT

The unstoppable spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has severely threatened public health over the past 2 years. The current ubiquitously accepted method for its diagnosis provides sensitive detection of the virus; however, it is relatively time-consuming and costly, not to mention the need for highly skilled personnel. There is a clear need to develop novel computer-based diagnostic tools to provide rapid, cost-efficient, and time-saving detection in places where massive traditional testing is not practical. Here, we develop an electrochemiluminescence (ECL)-based detection system whose results are quantified as reverse transcriptase polymerase chain reaction (RT-PCR) cyclic threshold (CT) values. A concentration-dependent signal is generated upon the introduction of the virus to the electrode and is recorded with a smartphone camera. The ECL images are used to train machine learning algorithms, and a model using artificial neural networks (ANNs) for 45 samples was developed. The model demonstrated more than 90% accuracy in the diagnosis of 50 unknown real samples, detecting up to a CT value of 32 and a limit of detection (LOD) of 10-12 g mL-1 in the testing of artificial samples.


Subject(s)
COVID-19 , Humans , COVID-19/diagnosis , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/genetics , Smartphone , Sensitivity and Specificity , Machine Learning , Immunoassay , Tomography, X-Ray Computed
12.
Viruses ; 14(11)2022 Nov 21.
Article in English | MEDLINE | ID: covidwho-2116086

ABSTRACT

Background: The transmissible capacity and toxicity of SARS-CoV-2 variants are continually changing. We report here the follow-up study of hospitalized COVID-19 patients from 2020 to 2022. It is known that the PCR diagnosis for hospitalized patients sometimes causes confusion because of the incompatibility between their diagnosis and symptoms. We applied our sugar chain-immobilized gold-nanoparticles for the extraction and partial purification of RNA from specimens for quantitative RT-PCR assay and evaluated whether the results correlate with patients' symptoms. Methods and Results: Saliva specimens were taken from hospitalized patients with mild or moderate symptoms every early morning. At the time of RT-PCR diagnosis, two methods for the extraction and partial purification of RNA from the specimen were performed: a commonly used Boom (Qiagen) method and our original sugar chain-immobilized gold nanoparticle (SGNP) method. For symptoms, body temperature and oxygen saturation (SpO2) of patients were monitored every 4 h. Conclusions: It was clear that patients infected with the Delta variant needed more time to recover than those with the Omicron variant, and that the SGNP method showed more realistic correlation with the symptoms of patients compared with the common Qiagen method.


Subject(s)
COVID-19 , Metal Nanoparticles , Humans , Reverse Transcriptase Polymerase Chain Reaction , Gold , SARS-CoV-2/genetics , Sugars , Follow-Up Studies , COVID-19/diagnosis , RNA, Viral/genetics , RNA, Viral/analysis , Sensitivity and Specificity , Carbohydrates
14.
J Infect Dis ; 226(10): 1743-1752, 2022 Nov 11.
Article in English | MEDLINE | ID: covidwho-2121302

ABSTRACT

BACKGROUND: Laboratory screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a key mitigation measure to avoid the spread of infection among recruits starting basic combat training in a congregate setting. Because viral nucleic acid can be detected persistently after recovery, we evaluated other laboratory markers to distinguish recruits who could proceed with training from those who were infected. METHODS: Recruits isolated for coronavirus disease 2019 (COVID-19) were serially tested for SARS-CoV-2 subgenomic ribonucleic acid (sgRNA), and viral load (VL) by reverse-transcriptase polymerase chain reaction (RT-PCR), and for anti- SARS-CoV-2. Cluster and quadratic discriminant analyses of results were performed. RESULTS: Among 229 recruits isolated for COVID-19, those with a RT-PCR cycle threshold >30.49 (sensitivity 95%, specificity 96%) or having sgRNA log10 RNA copies/mL <3.09 (sensitivity and specificity 96%) at entry into isolation were likely SARS-CoV-2 uninfected. Viral load >4.58 log10 RNA copies/mL or anti-SARS-CoV-2 signal-to-cutoff ratio <1.38 (VL: sensitivity and specificity 93%; anti-SARS-CoV-2: sensitivity 83%, specificity 79%) had comparatively lower sensitivity and specificity when used alone for discrimination of infected from uninfected. CONCLUSIONS: Orthogonal laboratory assays used in combination with RT-PCR may have utility in determining SARS-CoV-2 infection status for decisions regarding isolation.


Subject(s)
COVID-19 , Humans , COVID-19/diagnosis , SARS-CoV-2 , COVID-19 Testing , Sensitivity and Specificity , RNA , RNA, Viral/genetics , Reverse Transcriptase Polymerase Chain Reaction
15.
PLoS One ; 17(11): e0277301, 2022.
Article in English | MEDLINE | ID: covidwho-2109330

ABSTRACT

PURPOSE: To assess hospitalized COVID-19 inpatients for the prevalence of retinopathy and tear film SARS-CoV-2 RNA, and associated risk factors for their detection. METHODS: Hospitalized COVID-19 patients underwent dilated ophthalmic examination and fundus photography. Conjunctival swabs were assessed for SARS-CoV-2 RT-PCR via a triple target assay. We assessed the relationships of retinopathy with clinical outcomes, systemic risk factors and laboratory data. RESULTS: The median age was 59.5 years and 29 (48%) were female. Retinopathy associated with COVID-19 was observed in 12 of 60 patients (20%). The median age of patients with COVID-19 retinopathy was 51.5 compared to 62.5 years in individuals without retinopathy (p = 0.01). Median BMI was 34.3 in patients with retinopathy versus 30.9 in those without retinopathy (p = 0.04). Fifteen of 60 patients (25%) tested SARS-CoV-2 RNA-positive in their tear film without a relationship with timing of illness and hospitalization. The N2 gene was particularly sensitive with 18 of 19 eyes (94.7%) showing N2-positivity, including 2 patients with alpha variant-positivity (B.1.1.7). CONCLUSION: Retinopathy was observed in 20% of patients hospitalized for COVID-19. Patients with retinopathy were more likely to be younger and have higher BMI than hospitalized patients without retinopathy. Tear film SARS-CoV-2 RNA was detected in 25% of patients. The relationship of obesity and age with retinopathy requires further investigation.


Subject(s)
COVID-19 , Retinal Diseases , Humans , Female , Middle Aged , Male , COVID-19/diagnosis , SARS-CoV-2/genetics , RNA, Viral/genetics , RNA, Viral/analysis , Reverse Transcriptase Polymerase Chain Reaction , Risk Factors
16.
Indian J Pathol Microbiol ; 65(4): 907-910, 2022.
Article in English | MEDLINE | ID: covidwho-2100023

ABSTRACT

Context: COVID-19 caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is an emerging pandemic that is rapidly spreading with more than 114 million confirmed cases and 2.5 million deaths by far. Nasopharyngeal swab (NPS) in VTM has been used as the gold standard respiratory specimen for SARS-CoV-2 reverse-transcriptase real-time PCR (rRT-PCR) tests. But now the virus can also be detected in other clinical specimens like bronchoalveolar lavage, sputum, saliva, throat swab, blood, and stool specimens. Aims: The aim of this study was to determine the diagnostic potential of saliva as a sample in comparison to NPS for detection of SARS-CoV-2 by rRT-PCR. Settings and Design: A cross-sectional study was conducted among 256 paired samples (NPS and Saliva) received in the Department of Microbiology, SMS Medical College, Jaipur over a period of 2 months. Methods and Material: NPS from individuals were collected in a sterile tube containing Viral Transport Medium™. Before swab collection, whole saliva was collected by spitting from the suspected patient into a sterile container. Both were stored at room temperature and transferred to the diagnostic laboratory within four hours of collection where extraction was done using Perkin Elmer chemagic extractor and rRT- PCR was performed using NIV, Pune mastermix. Results: Sensitivity, specificity, PPV, and NPV of RT-PCR for the diagnosis of COVID-19 in saliva were 84.26%, 100%, 100%, and 54.05%, respectively. The accuracy of detection of COVID-19 by saliva samples compared to the routinely used NPS samples (considered as the standard reference) for RT PCR was 86.72%. Conclusions: Our results show that saliva as a reliable sample type for SARS-CoV-2 detection.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , Reverse Transcriptase Polymerase Chain Reaction , COVID-19/diagnosis , Saliva , Cross-Sectional Studies , Nasopharynx , India , Specimen Handling/methods
17.
J Clin Microbiol ; 60(1): e0174221, 2022 01 19.
Article in English | MEDLINE | ID: covidwho-2097916

ABSTRACT

Point-of-care antigen tests are an important tool for SARS-CoV-2 detection. Antigen tests are less sensitive than real-time reverse transcriptase PCR (rRT-PCR). Data on the performance of the BinaxNOW antigen test compared to rRT-PCR and viral culture by symptom and known exposure status, timing during disease, or exposure period and demographic variables are limited. During 3 to 17 November 2020, we collected paired upper respiratory swab specimens to test for SARS-CoV-2 by rRT-PCR and Abbott BinaxNOW antigen test at two community testing sites in Pima County, Arizona. We administered a questionnaire to capture symptoms, known exposure status, and previous SARS-CoV-2 test results. Specimens positive by either test were analyzed by viral culture. Previously we showed overall BinaxNOW sensitivity was 52.5%. Here, we showed BinaxNOW sensitivity increased to 65.7% among currently symptomatic individuals reporting a known exposure. BinaxNOW sensitivity was lower among participants with a known exposure and previously symptomatic (32.4%) or never symptomatic (47.1%) within 14 days of testing. Sensitivity was 71.1% in participants within a week of symptom onset. In participants with a known exposure, sensitivity was highest 8 to 10 days postexposure (75%). The positive predictive value for recovery of virus in cell culture was 56.7% for BinaxNOW-positive and 35.4% for rRT-PCR-positive specimens. Result reporting time was 2.5 h for BinaxNOW and 26 h for rRT-PCR. Point-of-care antigen tests have a shorter turnaround time than laboratory-based nucleic acid amplification tests, which allows for more rapid identification of infected individuals. Antigen test sensitivity limitations are important to consider when developing a testing program.


Subject(s)
COVID-19 , SARS-CoV-2 , Antigens, Viral , Humans , Reverse Transcriptase Polymerase Chain Reaction , Sensitivity and Specificity
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