Performance Evaluation of the STANDARD i-Q COVID-19 Ag Test with Nasal and Oral Swab Specimens from Symptomatic Patients.

Publication date: Jan 22, 2024

We evaluated the diagnostic performance of the STANDARD i-Q COVID-19 Ag Test, which was developed to detect viral antigens, using nasal and oral swabs. Sixty positive and 100 negative samples were analyzed. We determined the distribution of the Ct values according to the day of sample collection after symptom onset, the diagnostic performance of the total samples and subgroups separated by Ct value or time of sample collection, and the Ct value at which maximal accuracy was expected. No differences were observed in Ct values, except for the samples obtained on the day of symptom onset. The diagnostic sensitivity and specificity of the oral swabs were 75. 0 and 100. 0%, respectively, whereas those of the nasal swabs were 85. 0 and 98. 0%, respectively. The sensitivity was higher in samples with a high viral load collected earlier than those collected later, although the difference was not significant. False-negative results were confirmed in all samples with a Ct value ≥ 30. 0. These results indicate that tests using oral and nasal swabs are helpful for diagnosing acute symptomatic cases with suspected high viral loads. Our tests exhibited relatively low sensitivity but high specificity rates, indicating the need to assess negative antigen test results.

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Concepts Keywords
Antigens COVID-19
Basel nasal swab
Covid oral swab
Helpful performance evaluation
point-of-care testing


Type Source Name
disease MESH COVID-19
disease IDO symptom
disease VO time
disease MESH Infection
disease VO Severe acute respiratory syndrome coronavirus 2
drug DRUGBANK Gold
drug DRUGBANK Coenzyme M
drug DRUGBANK Methionine
disease VO organization
disease IDO infection prevalence
disease VO effective
disease MESH sore throat
disease MESH pneumonia

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