Specimens were collected from an almost exclusively adult population with an average age of 54 years (S.D. Samples tested were nasopharyngeal flocked swab samples transported in universal transport medium (for all samples other than those initially tested for SARS-CoV-2) or saline (for SARS-CoV-2 comparisons). Here, we describe characterization of accuracy, precision, and limit of detection of the Alinity m Resp-4-Plex assay determined as part of normal quality assurance activities prior to adoption for clinical use in our clinical laboratory. They are used along with the inflection point of the amplification curve at the maximum amplification efficiency (the max ratio) ( Shain and Clemens, 2008) for qualitative assessment of target positivity and negativity (personal communication, Joshua Kostera, Abbott Molecular). Cycle threshold numbers (Ct) determined on the Alinity m instrument in the Resp-4-Plex assay are determined based on a fluorescence cutoff. The primers and probes for the SARS-CoV-2 targets are the same as those used in the singleplex Abbott RealTime SARS-CoV-2 and Alinity m SARS-CoV-2 assays, whose performance characteristics have been examined in prior literature ( Arnaout et al., 2021 Hirschhorn et al., 2021 Smith et al., 2020). Each amplicon is detected by a real-time probe with a distinct fluorophore with the exception that probes for both SARS-CoV-2 targets are detected with the same fluorophore. An internal control is spiked into each sample in the form of armored RNA encoding a segment of the hydroxypyruvate reductase gene from the pumpkin plant, Cucurbita pepo it controls for appropriate extraction and amplification in each reaction. The multiplex, reverse-transcription real-time PCR assay targets the RdRp and N genes of SARS-CoV2 the matrix gene of influenza A the nonstructural 1 gene of influenza B and the matrix gene of RSV. Approved sample types are either a nasopharyngeal swab collected by a healthcare provider or a nasal swab specimen self-collected in a healthcare setting submitted in viral transport medium or saline. The Abbott Alinity m Resp-4-Plex assay in March 2021 received emergency use authorization designation for detection of SARS-CoV-2, influenza A, influenza B and RSV. It will therefore be critical to be able to test both patients and symptomatic staff for high consequence respiratory pathogens to avert potential nosocomial transmission and to identify the most advantageous therapeutic options for patients with serious illness.Ī multiplex testing option for high-consequence testing would address these specific diagnostic needs. At the same time, SARS-CoV-2 will likely become endemic, potentially adopting a seasonal cycle with enhanced transmission during the winter, as observed in the United States during the winters of 20 ( Byun et al., 2021). Presumably, however, with less than 100% vaccine efficacy for influenza, waning immunity to circulating respiratory viruses over a large population cohort, and reopening of society, circulation of influenza and RSV may rebound and even exceed normal levels for a period of time ( Baker et al., 2021). With social distancing and masking during the COVID pandemic, the circulation of influenza and other respiratory viruses almost ceased in many locations ( Olsen et al., 2006). Therefore, sensitive detection and differentiation of these viruses are valuable clinical determinations. Depending on the stage of illness, there are therapeutics with varying efficacy for SARS-CoV-2, influenza, and RSV. RSV, although primarily thought of as a serious pathogen in young children, can also cause bronchiolitis and pneumonia in adults. SARS-CoV-2 and influenza, especially, have significant implications in terms of transmission inside and outside of hospital settings and therefore require reliable methods for diagnosis. Respiratory disease signs and symptoms for these viruses overlap, and, therefore, it is not possible to reliably differentiate between them on clinical grounds alone, especially early during the course of disease. SARS-CoV-2, influenza A/B, and RSV may cause respiratory infection with significant morbidity and mortality.
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