Multicenter evaluation of the Panbio COVID-19 Rapid Antigen-Detection Test for the diagnosis of SARS-CoV-2 infection (preprint)

The standard RT-PCR assay for COVID-19 is laborious and time-consuming, limiting the availability of testing. Rapid antigen-detection tests are faster and less expensive; however, the reliability of these tests must be validated before they can be used widely. The objective of this study was to determine the reliability of the PanbioTM COVID-19 Ag Rapid Test Device (PanbioRT) (Abbott) for SARS-CoV-2 in nasopharyngeal swab specimens. This was a prospective multicenter study in ten Spanish university hospitals of patients from hospital units with clinical symptoms or epidemiological criteria for COVID-19. Patients whose onset of symptoms or exposure was more than 7 days earlier were excluded. Two nasopharyngeal exudate samples were taken to perform the PanbioRT and a diagnostic RT-PCR test. Among the 958 patients studied, 359 (37.5%) were positive by RT-PCR and 325 (33.9%) were also positive by the PanbioRT. Agreement was 95.7% (kappa score: 0.90). All 34 false-negative PanbioRT results were in symptomatic patients, with 23.5% of them at 6-7 days since the onset of symptoms and 58.8% presenting CT >30 values for RT-PCR, indicating a low viral load. Overall sensitivity and specificity for the PanbioRT were 90.5% and 98.8%, respectively. The PanbioRT provides good clinical performance as a point-of-care test, with even more reliable results for patients with a shorter clinical course of the disease or a higher viral load. While this study has had a direct impact on the national diagnostic strategy for COVID-19 in Spain, the results must be interpreted based on the local epidemiological context.

Detection of SARS-CoV-2 antibodies is insufficient for the diagnosis of active or prior COVID-19 (preprint)

We assessed the performance of Abbott's SARS-CoV-2 IgG assay and the PanbioTM COVID-19 IgG/IgM rapid test device for the diagnosis of active and past/cured COVID-19. Three cohorts of patients were chosen. Cohort 1, patients (n=65) who attended the emergency department on March 30, 2020 with clinical suspicion of active COVID-19 (n=56 with proven/probable COVID-19). Cohort 2, hospital workers (n=92) who had either been (n=40) or not (n=52) diagnosed with proven/probable COVID-19 and were asymptomatic at the time of the sampling. Cohort 3, patients (n=38) cared at the hospital before the start of the COVID pandemic. Detection of serum antibodies was done using Abbott´s SARS-CoV-2 IgG assay and the PanbioTM COVID-19 IgG/IgM device. Both methods showed 98% agreement for IgG detection. No antibodies were detected in the 38 samples from hospitalized pre-COVID subjects. The diagnostic performance of IgGs detected by Abbott´s SARS-CoV-2 assay in Cohorts 1/2 was: sensitivity (60.7%/75%) and specificity (100%/84.6%). The diagnostic performance of IgM by PanbioTM COVID-19 in Cohorts 1/2 was: sensitivity (16%/17.5%) and specificity (100%/98.1%). We show that IgG detection alone is insufficient for the diagnosis of active or past COVID-19. IgM detection has a limited diagnostic value.