Abstract
Objective: To determine the sensitivity and specificity of the Abbott ID-NOWTM test in the diagnosis of COVID-19. The test is based on the detection of the SARS-CoV-2 gene by isothermal amplification technology.
Methods: From 303 individuals, two nasopharyngeal swabs and one oropharyngeal swab were collected to be tested in parallel by the ID-NOWTM test and PCR test (AllplexTM SARS-CoV-2 Assay). A subgroup of 107 individuals presented to the public collection point for covid-19 at the Motol University Hospital during the dominance of the Delta variant, and the others were tested via the Adult Emergency Admission Department during the dominance of the Omicron variant.
Results: Of 297 valid samples, 43 were positive by the PCR assay and 33 were positive by the ID-NOWTM test (sensitivity 76.74%; 95% CI 61.37 to 88.24%). ID-NOWTM detected three samples as positive, but the positivity was not confirmed by PCR (specificity 98.82%; 95% CI 96.59 to 99.76%).
A significant increase in sensitivity up to 100% is observed for samples with a higher viral load (with a PCR threshold cycle value below 30 or from patients with symptoms of COVID-19). The Delta or Omicron variant has no significant effect on the sensitivity of the test.
Conclusion: Due to its ease of use and speed of result, ID-NOWTM is a suitable diagnostic tool for prompt assessment of a patient's infectivity. If, despite the negative ID-NOWTM result, the patient has symptoms of COVID-19, it is advised to perform a classic PCR test for SARS-CoV-2.