Although we had all hoped we might not reach this pandemic point again, much of the world is seeing rising numbers of coronavirus disease 2019 (COVID-19) cases. Healthcare systems across the United States and elsewhere are strained, and the findings of Mansbridge et al ^{Reference Mansbridge, Tanner and Beard1} regarding the use of FebriDx (Lumos Diagnostics, Sarasota, FL) in the emergency department (ED) to quickly separate patients infected with severe acute respiratory coronavirus virus 2 (SARS-CoV-2) from other patients provides us with a welcome tool in our hospital management of COVID-19.

The SARS-CoV-2 omicron variant is ∼3.3 times more transmissible than the previous delta variant, and it has created a surge that has overwhelmed hospitals worldwide since November 2021. ^{Reference Ito, Piantham and Nishiura2,Reference Nishiura, Ito, Anzai, Kobayashi, Piantham and Rodríguez-Morales3} The United States is now recording >800,000 COVID-19 cases per day, and this is likely an underestimate given the high number of rapid tests being performed outside healthcare settings that report results. ⁴ Although many of these cases are asymptomatic or mild and do not prompt a visit to the ED, many of them are more severe, and do. Additionally, when the community prevalence of the disease is high, the number of people incidentally infected with severe acute respiratory coronavirus virus 2 (SARS-CoV-2) that need to visit the ED for other reasons is high as well.

The influx of COVID-19 patients into EDs during the current omicron surge has exacerbated the long-standing problem of ED overcrowding. ^{Reference Badr, Nyce, Awan, Cortes, Mowdawalla and Rachoin5} Burnt-out healthcare workers and those who may be absent due to quarantine, isolation, or caring for a child whose school has been canceled lead to shortages of staff. ^{Reference Iacobucci6,7} This shortage frequently results in insufficient capacity to open certain areas of the ED where isolation rooms might exist. Nationwide, this situation has led to EDs to resort to using hallway spaces for patient care. ^{Reference Chekenjian8,9} Patients may wait anywhere from 2 to 6 hours before seeing a provider and continue to receive care in those spots even longer. Those who need to be admitted remain in the ED while waiting for inpatient hospital beds to become available and, in some hospitals, admitted patients are being boarded in the ED for days due to a lack of beds elsewhere.

Unfortunately, the symptoms of SARS-CoV-2 are protean and not easily distinguished from other disease entities. Thus, patients with mixed infection status may be placed in stretchers near each other. Consistently wearing a mask for long periods of time while in this setting can be very challenging for patients, particularly those who are very ill. All these factors make preventing nosocomial transmission challenging, particularly in high-prevalence areas, as we are seeing throughout much of the United States. For example, in New York City at the peak of the omicron surge, 31% of patients tested for SARS-CoV-2 were positive. ¹⁰

Quickly identifying and isolating patients with COVID-19 individually or in cohorts could dramatically reduce nosocomial transmission in the ED. However, we cannot rely on methods used earlier in the pandemic, such as temperature checks and symptom screeners, which have proven to be largely ineffective. ^{Reference Wright and Mackowiak11,Reference Callahan, Steinberg, Fries, Gombar, Patel, Corbin and Shah12} Even more advanced clinical algorithms that incorporate laboratory and imaging data are not very accurate in determining the likelihood of a patient having COVID-19. ^{Reference DiLorenzo, Davis and Dugas13} This situation is expected to be even more prevalent with the omicron variant, given the high number of asymptomatic patients. ^{Reference Garrett, Tapley and Andriesen14} By contrast, rapid point-of-care tests (POCTs), with their turnaround time of 10–15 minutes, may be used to quickly identify and isolate patients with COVID-19. ^{Reference Boum, Fai, Nikolay and Mboringong15} In their manuscript, Mansbridge et al ^{Reference Mansbridge, Tanner and Beard1} studied the use of 1 POCT, the lateral flow assay FebriDx, which has been designed to distinguish between bacterial and viral illnesses. They studied its utilization in a high prevalence setting, similar to circumstances we are now seeing in some areas of the United States during the omicron surge, and they found it to be useful in decreasing time spent in high-risk, cohorted areas of the ED, among patients who were triaged there due to concern for COVID-19.

Although FebriDx currently has not been approved by the US Food and Drug Administration for use in the United States, other point-of-care (POC) lateral-flow assays have been approved, particularly various antigen tests. This class of tests has similarly been shown to have a high sensitivity and negative predictive value in detecting infectious virus, ^{Reference Mina, Parker and Larremore16–Reference Turcato, Zaboli and Pfeifer18} and these test may be considered for use in a manner similar to FebriDx. The SARS-CoV-2 antigen test has an advantage over assays that are less specific in detecting a particular virus. As the prevalence of respiratory viruses other than SARS-CoV-2 increases, a SARS-CoV-2 antigen test would allow for more accurate placement of patients in cohorts.

Another major advantage of using rapid POC assays, either antigen or antiviral host-response tests, during the initial ED visit is that they are less likely than PCR testing to pick up residual virus from a prior infection in patients who have recovered from COVID-19. Therefore, rapid tests can also help prevent unnecessary use of isolation rooms on medical floors and intensive care units in hospitals with limited space. This was the case in the study by Mansbridge et al, ^{Reference Mansbridge, Tanner and Beard1} in which using FebriDx reduced the number of patients unnecessarily placed in isolation by 60% and allowed clinical areas to be reconfigured and for previously suspended ED services to begin again. Adding FebriDx to clinical triage also significantly reduced the need for isolation rooms in another study. ^{Reference Houston, Deas and Naik19} In the Mansbridge study, ^{Reference Mansbridge, Tanner and Beard1} only 29 patients who tested negative were later positive; 12 (43%) had a cycle threshold (Ct) value >35 and 7 (24%) had had a diagnosis of COVID-19 >14 days before admission. Similarly, if a patient has a negative antigen test, it is unlikely that they are very contagious, and providers can feel confident in using rapid POCTs to make decisions about which patients should be prioritized for isolation.

Finally, with the advent of effective COVID-19 therapeutics, including monoclonal antibodies and antiviral agents that need to be administered early in the course of illness, tension has developed between wanting to move patients quickly from the ED if they do not need to be there and providing COVID-19 diagnoses of quickly so that they are eligible to receive medications when they are most likely to improve outcomes. ^{Reference Gupta, Gonzalez-Rojas and Juarez20,Reference Mahase21} The high positive predictive value of the antigen tests makes them appropriate for this use as well, and patients who are well enough to be discharged from the ED would not need to substantially prolong their visit waiting for a PCR test.

The omicron surge is currently taxing healthcare systems worldwide and disrupting many other clinical services, such as surgeries necessary to diagnose malignancy and detection of other viruses such as hepatitis C. ^{22,Reference Sperring, Ruiz-Mercado and Schechter-Perkins23} In the United States, the overall death rate has been higher than predicted throughout the pandemic, and some of these deaths may be due to delayed care. ^{Reference Lai, Pasea and Banerjee24} Although both public health entities and individual healthcare systems are long overdue for infrastructure upgrades that would allow us to manage a pandemic of this magnitude more effectively, we need a short-term solution to accurately identify patients with COVID-19, to isolate them from other patients to prevent infection transmission, and to free up necessary clinical space so that we can continue to provide high-quality care during this surge and any future surges. Rapid point-of-care SARS-CoV-2 testing early in ED care has the potential to be part of this solution.