Why it’s crucial to differentiate between COVID-19, flu, and RSV
November 2021 – The Journal of Healthcare Contracting
Due to the ongoing pandemic, there is significant emphasis on diagnostic testing in laboratory medicine for flu, RSV, and COVID-19. “While many of the signs and symptoms of infections caused by these viruses are similar, the treatments and patient interventions for infections caused by SARS-CoV-2, influenza virus, and RSV are different,” said Michael Loeffelholz, Ph.D., Senior Director, Medical Affairs for Sunnyvale, Calif.-based Cepheid, a molecular diagnostics company. “Infected, hospitalized patients are often cohorted, and even in the urgent care and physician office settings, antiviral agents are often prescribed for influenza infections, making accurate diagnosis important,” Dr. Loeffelholz said.
Cepheid has responded to the COVID-19 pandemic by developing fast and accurate tests for SARS-CoV-2, including the Xpert® Xpress CoV-2/Flu/RSV plus (4-plex plus) test that detects SARS-CoV-2, Influenza A, Influenza B, and Respiratory syncytial virus (RSV) all in a single test. Studies have shown Cepheid’s SARS-CoV-2 tests to be among the most accurate available.1,2 Cepheid’s test systems are scalable from the point of care to the high volume core laboratory. Importantly, the same Cepheid SARS-CoV-2 test can be used at both point of care and in the core laboratory, providing near-patient testing accuracy equivalent to that of large batch-based platforms.3
Accuracy and efficiency
Cepheid’s 4-plex test has been shown to provide high accuracy, equivalent to that of Cepheid tests that separately detect SARS-CoV-2, Flu and RSV.4,5 Cepheid’s 4-plex plus test is the latest generation and exemplifies Cepheid’s proactive approach to address increasing genetic diversity of SARS-CoV-2.
“The 4-plex plus will improve operational efficiencies by combining four important viral targets in a single test,” Dr. Loeffelholz said. “This means fewer patient specimens to collect and laboratory tests to perform, compared to separate tests for these viruses.”
SARS-CoV-2, influenza viruses, and RSV cause upper and lower respiratory tract diseases that have many overlapping signs and symptoms.6 Additionally, surges of COVID-19 have occurred during the winter months, when influenza and RSV incidence are usually at their highest. These viruses each have unique treatment or patient management pathways. These factors demonstrate the value of multiplexing SARS-CoV-2, influenza A, influenza B, and RSV in a single test.
Among other enhancements, Cepheid’s 4-plex plus test adds a third genetic target for SARS-CoV-2. Detection of any of the nucleocapsid, envelope, or RNA-dependent RNA polymerase gene targets will produce a positive result for SARS-CoV-2. Cepheid’s 4-plex plus test includes three genetic targets for SARS-CoV-2 for broad coverage of lineages and variants, including the Delta Variant of Concern, and to mitigate future genetic drift. Additionally, the test incorporates multiple genetic targets for influenza viruses. As such, the 4-plex plus test is well positioned to detect both current and future emerging strains of SARS-CoV-2 and influenza viruses.
Indeed, Cepheid’s 4-plex plus test is fast, accurate, and scalable from the point of care to the high-volume core laboratory. The point-of-care and laboratory test systems use the same reagents, providing point-of-care test performance equivalent to that observed in the reference laboratory. Incorporation of multiple genetic targets for SARS-CoV-2 and influenza allows broad strain, variant, and subtype coverage, and make Cepheid’s 4-plex plus an excellent long-term solution for detection of these important respiratory viruses. SARS-CoV-2, influenza viruses, and RSV may co-circulate in the community. Additionally, signs and symptoms of infections caused by these viruses can be similar, making accurate laboratory diagnosis important.
1 Zhen W, Smith E, Manji R, Schron D, Berry GJ. Clinical Evaluation of Three Sample-to-Answer Platforms for Detection of SARS-CoV-2. J Clin Microbiol. 2020 Jul 23;58(8).
2 Wolters F, van de Bovenkamp J, van den Bosch B, van den Brink S, Broeders M, Chung NH, et al. Multi-center evaluation of cepheid xpert® xpress SARS-CoV-2 point-of-care test during the SARS-CoV-2 pandemic. J Clin Virol. 2020 Jul;128:104426.
3 Stevens B, Hogan CA, Sahoo MK, Huang C, Garamani N, Zehnder J, et al. Comparison of a Point-of-Care Assay and a High-Complexity Assay for Detection of SARS-CoV-2 RNA. J Appl Lab Med. 2020 Nov 1;5(6):1307–1312.
4 Leung EC-M, Chow VC-Y, Lee MK-P, Tang KP-S, Li DK-C, Lai RW-M. Evaluation of the Xpert Xpress SARS-CoV-2/Flu/RSV Assay for Simultaneous Detection of SARS-CoV-2, Influenza A and B Viruses, and Respiratory Syncytial Virus in Nasopharyngeal Specimens. J Clin Microbiol. 2021 Mar 19;59(4).
5 Mostafa HH, Carroll KC, Hicken R, Berry GJ, Manji R, Smith E, et al. Multicenter Evaluation of the Cepheid Xpert Xpress SARS-CoV-2/Flu/RSV Test. J Clin Microbiol. 2021 Feb 18;59(3).
6 https://www.cdc.gov/flu/symptoms/flu-vs-covid19.htm?web=1&wdLOR=c5625922F-B970-4971-8702-F16D97311251