Clinical Performance of the cobas Liat SARS-CoV-2 & Influenza AB for the Detection of SARS-CoV-2 in Nasal Samples

Background and Objective

Point-of-care type molecular diagnostic tests have been used for detecting SARS-CoV-2, although their clinical utility with nasal samples has yet to be established. This study evaluated the clinical performance of the cobas Liat SARS-CoV-2 & Influenza AB (Liat) in nasal samples.

Methods

Nasal and nasopharyngeal samples were collected and were tested using the Liat, the cobas 6800 system and the cobas SARS-CoV-2 & Influenza AB (cobas), and a method developed by National Institute of Infectious Diseases, Japan (NIID).

Results

A total of 814 nasal samples were collected. The Liat assay was positive for SARS-CoV-2 in 113 (13.9%). The total, positive, and negative concordance rate between the Liat and cobas/NIID assays were 99.3%/98.4%, 99.1%/100%, and 99.3%/98.2%, respectively. Five samples were positive only using the Liat assay. Their Ct values ranged from 31.9 to 37.2. The Ct values of the Liat assay were significantly lower (p < 0.001) but were correlated (p < 0.001) with those of other molecular assays. In the participants who tested positive for SARS-CoV-2 on the Liat assay using nasopharyngeal samples, 88.2% of their nasal samples also tested positive using the Liat assay.

Conclusion

The Liat assay showed high concordance with other molecular assays in nasal samples. Some discordance occurred in samples with Ct values > 30 on the Liat assay.

Key Points

• The cobas Liat SARS-CoV-2 & Influenza AB assay showed high concordance with other molecular assays in nasal and nasopharyngeal samples, providing results within 20 minutes.

• Some discordance occurred in samples with Ct values > 30 on the Liat assay.

• The Liat assay may be suitable for use in a variety of clinical situations, primarily where accurate detection of SARS-CoV-2 is necessary.