In December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in patient cases in Wuhan, China. The contagious disease rapidly spread worldwide, leading to the COVID-19 pandemic. As a result, many molecular assay developers scrambled to add a sensitive and specific COVID-19 test to existing platforms. Several systems were authorized under the Emergency Use Authorization (EUA) approval status.
For obvious reasons (e.g., proper treatment and isolation precautions), it became imperative for hospital ICUs and Emergency Departments to distinguish between FLU and COVID respiratory infections as quickly as possible.
As mentioned, several molecular PCR platforms and assay developments occurred in rapid succession, including platforms validated for nasal/nasopharyngeal swabs or nasal wash/aspirate samples. Two targets, E and N2, are frequently used. Recently, well-known manufacturers added Flu A, Flu B, and RSV to the SARS-CoV-2—four tests (multiplex) in a single test process. Note: 2009 H1N1 is no longer reported separately from most platform results, as this flu has become part of seasonally circulating FluA.
Several popular rapid-testing molecular platforms now detect nucleic acid from SARS-CoV-2. Respiratory swab specimens are usually utilized. As an alternative, panels have been developed. Several multiplex panels on well-known platforms now perform rapid screens simultaneously for as many as 22 viral and bacterial pathogens causing respiratory infections, including SARS-CoV-2. Although costly, many of these rapid tests save time in diagnosing patients and are easy to use, eliminating the need to send specimens to referral laboratories for extensive viral workups.
Note: Several other vendors (too numerous to cover this course's scope) are geared toward rapid testing in the clinical microbiology laboratory and have been approved by the FDA or are under development. These vendors use the primers and probes recommended by the CDC to detect SARS-CoV-2 by RT-PCR.
