Looking to the Future: The Value of Multiplex Assays for Timely and Accurate Treatment

In July of 2021, the CDC announced the imminent phase-out of their singularly focused SARS-CoV-2 RT-PCR test, emphasizing that labs should now consider adoption of multiplexed testing in its place. As flu season gets underway, more labs are likely to follow suit.⁵

The current standard for COVID testing is singleplex (meaning one target) polymerase chain reaction (PCR), which amplifies small amounts of viral material to detect only SARS-CoV-2. Alternatively, rapid antigen swabs are available for at-home use and provide results in about 15 minutes. However, these are considered less sensitive and require a higher viral load for a positive result.⁶

Additionally, both of these testing options only detect the presence of one pathogen, which can lead providers to inefficient downstream testing, incurring greater costs for the patient while wasting valuable time. Adding to this flaw, researchers found that over 20% of patients with COVID-19 were co-infected with another respiratory pathogen, making it more vital than ever that providers have an effective way of simultaneously screening for multiple pathogens. ⁶

"There is an increasing demand for technologies that can extract large amounts of bioinformation from a limited sample volume for better diagnosis, prognosis and treatment of diseases."

Benefits for the Patient

Currently physician appointments last ~15 mins with younger generations preferring shorter appointments so often choose Urgent Care clinics rather than traditional doctor offices. There is an increasing demand for technologies that can extract large amounts of bioinformation from a limited sample volume for better diagnosis, prognosis and treatment of diseases.¹ The development of multiplex tests allows the simultaneous measurement of multiple analytes in a single biological sample with minimal assay time, cost, and sample volume. For example, a multiplex test for respiratory viruses could yield sensitive, accurate results while the patient is in the doctor’s office. Treatment could begin immediately.

The Right Treatment for the Right Diagnosis

While relatively rare, false-negatives in SARS-CoV-2 testing can occur, regardless of whether tests are antigen- or PCR-based; most viral diagnostics have an associated false-negative rate.³ It’s also possible that a patient who is symptomatic of COVID-19 is instead infected with one of many other circulating respiratory viruses, such as influenza A or influenza B. With current testing so narrowly focused on SARS-CoV-2, physicians presented with a negative COVID-19 test lack the diagnostics needed to identify the cause of the patient’s symptoms.

While respiratory illnesses can present similarly, their treatment can vary dramatically.⁴ Influenza infections, for example, can be treated with antivirals, such as oseltamivir, to reduce the period of infection. But that same medication is markedly less effective against other respiratory pathogens. Case in point, remdesivir, not oseltamivir, is approved as a therapy for more severe COVID-19 cases. Likewise, people with severe COVID-19 cases can be prescribed dexamethosone, a steroid, or Interleukin-6 inhibitors to arrest runaway inflammatory responses in the lungs, a precursor to the acute respiratory distress syndrome. But those medications are well known to predispose influenza patients to secondary infections, due to their immuno-suppressive qualities.

Benefits for Labs

Multiplex testing helps laboratories conserve important testing supplies, such as pipettes, swabs and reagents, all of which remain in high demand.² Moreover, multiplex testing decreases the need for single-use tests and allows labs to provide more comprehensive results in less time.

Rapid multiplex testing has been shown to reduce the length of stay (LOS) for patients in the ICU from 9.2 to 6.2 days (P < 0.0001). In a time of boarding and hospital overcrowding, a shorter LOS for those hospitalized during “tripledemics” increases patient flow, therefore improving hospital productivity and patient satisfaction.⁷

In times of infectious disease surges, hospitals may become saturated with sick patients. Multiplex testing allows providers to quickly make informed decisions about optimal treatment plans, which may lead to a smaller backlog of patients waiting to be seen during times of limited healthcare resources.⁹

In addition, multiplex testing can help reduce antimicrobial resistance. When providers are uncertain of the course of treatment, it is common for unnecessary antibiotic prescriptions to occur. Since antibiotics are an ineffective treatment for viral illnesses, supply is stretched thin during surges. With quick identification of the pathogens in an infected patient, there is a lower chance that patients will be overprescribed antibiotics and a faster turnaround time to optimal treatment and thus discharge from the hospital.⁸

References

1. Monoplex and multiplex immunoassays: approval, advancements and alternatives, Comparative Clinical Pathology
2. Value of Multiplex Testing in Response to COVID-19, Flu Season, American Clinical Laboratory Association
3. Multiplex testing helps provide critical insights as respiratory viruses surge, Nature Portfolio
4. Ibid
5. Ibid
6. Technology in Action: Multiplex PCR in the Tripledemic, Himmelfarb Health Sciences Library, The George Washington University
7. Ibid
8. Ibid
9. Ibid

Contributors: Aashish Rathod and Steve Cox, SEKISUI Diagnostics Product Management