Diagnosing SARS-CoV-2 with Antigen Testing, Transcription-Mediated Amplification and Real-Time PCR.

This study was performed as a head-to-head comparison of the performance characteristics of (1) two SARS-CoV-2-specific rapid antigen assays with real-time PCR as gold standard as well as (2) a fully automated high-throughput transcription-mediated amplification (TMA) assay and real-time PCR in a latent class analysis-based test comparison without a gold standard with several hundred samples in a low prevalence "real world" setting. Recorded sensitivity and specificity of the NADAL and the LumiraDx antigen assays and the Hologic Aptima SARS-CoV-2 TMA assay were 0.1429 (0.0194, 0.5835), 0.7644 (0.7016, 0.8174), and 0.7157 (0, 1) as well as 0.4545 (0.2022, 0.7326), 0.9954 (0.9817, 0.9988), and 0.9997 (not estimable), respectively. Agreement kappa between the positive results of the two antigen-based assays was 0.060 (0.002, 0.167) and 0.659 (0.492, 0.825) for TMA and real-time PCR. Samples with low viral load as indicated by cycle threshold (Ct) values > 30 were generally missed by both antigen assays, while 1:10 pooling suggested higher sensitivity of TMA compared to real-time PCR. In conclusion, both sensitivity and specificity speak in favor of the use of the LumiraDx rather than the NADAL antigen assay, while TMA results are comparably as accurate as PCR, when applied in a low prevalence setting.

There is no intraocular affection on a SARS-CoV-2 - Infected ocular surface.

PURPOSE: The presence of SARS-CoV-2 RNA in anterior chamber fluid and/or the vitreous in patients with SARS-CoV-2 RNA on the ocular surface is unclear. Knowledge about the infectious state of intraocular structures could influence the daily work of ophthalmic surgeons. OBSERVATIONS: We analyzed ocular samples from a patient who had succumbed to COVID-19 pneumonia for the prevalence of SARS-CoV-2 RNA. We detected viral RNA in the ocular-surface samples on one swab and in one excidate from the conjunctiva. Samples from the anterior chamber and vitreous revealed no SARS-CoV-2 RNA. CONCLUSIONS: SARS-CoV-2 can effectively be inactivated with standard disinfection agents. The now proven absence of SARS-CoV-2 in intraocular fluids could influence how ophthalmic surgeons work. Without having to account for the risk of a contagion via the anterior chamber and/or vitreous body, the surgical staff would require no additional, more elaborate protection.