Comanaging Flu & COVID-19 Testing in 2021

March 2021 - Vol.10 No. 3 - Page #2

Q&A with Eugenio Zabaleta, PhD

OhioHealth Mansfield Hospital

Mansfield, Ohio


MedicalLab Management: Given the unknowns introduced by the Coronavirus pandemic, how has influenza testing been affected in your institution?

Eugenio Zabaleta: If we analyze the historical data from various influenza seasons in the past, we know each season is different and presents unique challenges, such as those associated with H1N1 (2009) or H3N2 (2011-2012). However, the complications introduced by the SARS-CoV-2 pathogen render this a completely different situation from what we have seen in living memory; one that requires a unique testing approach all together.

MLM: How have precautions such as the use of masks and social distancing etiquette affected flu and rhinovirus numbers this year for you?

Zabaleta: When I compare the current season’s data of confirmed influenza-associated hospitalization for my state (Ohio) to the last 5 years’ average, this is obviously an outlier season and the numbers are astonishing (see FIGURE 1). In my opinion the use of masks and social distancing in public is directly impacting what we see in the laboratory and in our emergency departments (EDs). The positivity rate for flu and cold viruses is very low, which is good news, of course, because the spike in COVID-19 cases has kept hospitals across the country on high alert and any reduction in the spread of communal viruses will benefit us, overall. Likewise, rapid treatment of COVID-19-positive patients and efforts to reduce the duration of contagion will be necessary in the long run.

While there is little long-term expectation of persistent mask-wearing or substantial social distancing going well into the future, hopefully the general public will continue with other, every-day hygienic practices, such as regular hand washing and avoiding touching of the face.

Click here to view a larger version of this Figure

MLM: While influenza and coronavirus are caused by different viral pathogens, what similarities pose challenges for laboratory testing?

Zabaleta: Both COVID-19 and influenza share several common symptoms including fever, chills, cough (usually dry in the case of COVID-19), difficulty breathing, fatigue, sore throat, runny nose, body aches and muscle pain, headache, etc. These are in addition to vomiting and diarrhea, which are more common in children than adults. Clearly, these shared symptoms can make it difficult to differentiate between them based on symptoms alone. Again, the depressed rate of flu and RSV this year is fortunate, as many people who might display symptoms of the flu (which can certainly be deadly on its own) may not seek appropriate medical care when they actually have coronavirus.

In an interesting twist, the somewhat unique symptoms of loss of taste and smell can aid in a differential diagnosis when considering flu versus COVID-19. The US CDC expands upon the relationship between flu and COVID-19 on its website.1

MLM: What other factors should laboratories consider when planning flu and COVID-19 testing strategies moving forward?

Zabaleta: Given the difficulty in differentiating between flu and COVID-19 based on symptoms alone, finding the right combination of test options and platforms has become quite important. There are numerous possible combinations from an array of solutions, including combination tests (Influenza A, B, and SARS-CoV-2), individual tests for each of these viruses, point-of-care platforms, and high- or medium-throughput chemistry and immunoassay instruments in a central or satellite laboratory. As patient populations differ from area to area, and COVID-19 rates remain high while flu rates remain relatively low, each laboratory must strike a balance that works for their institution and patient demographics.

Regardless, it is worth noting that due to the wide range of clinical patient management structures and patient throughput demands, the institution and the laboratory will likely need a combination of testing options available at all times moving forward. The ED often needs rapid results (ie, POCT), while PAT (pre-admission testing) operations can benefit from high-throughput platform results, as these can be done in batches according to a schedule and can be isolated from other urgent care testing.

Furthermore, distinguishing between symptomatic and asymptomatic patients remains important, as with symptomatic patients, a combination test makes the most sense (to help front line clinicians differentiate between flu and COVID-19), whereas in the asymptomatic PAT testing scenario, a single SARS-CoV-2 is the more reasonable option (ie, screening for COVID-19).

MLM: How does it appear that COVID-19 affects a patient’s susceptibility to other upper respiratory issues (eg, flu, RSV, pneumonia) or other issues such as sepsis or even C. difficile?

Zabaleta: We know that patients positive for COVID-19 could develop further complications, including:1

  • Respiratory failure
  • Acute respiratory distress syndrome (fluid in the lungs)
  • Pneumonia
  • Sepsis
  • Multiple-organ failure (eg, respiratory failure, kidney failure, shock)
  • Worsening of chronic medical conditions involving the lungs, heart, or nervous system (including diabetes)
  • Inflammation of the heart, brain, or muscle tissues
  • Cardiac injury (heart attack, stroke)
  • Secondary bacterial infections

One risk factor associated with COVID-19 is secondary bacterial pneumonia and C. diff (or any other pathogen) infection can result from the use of antibiotics to treat such a secondary infection; a process that remains interesting. A research letter to the CDC’s Emerging Infectious Diseases Journal described 9 cases of co-infection with SARS-CoV-2 and C. difficile.2 The letter highlighted the need for thoughtful and judicious use of antibiotics, especially in COVID-19-positive patients who demonstrate a substantial susceptibility to secondary bacterial infection. Given that antibiotics are known to have unintended consequences, they must be used only when clinically indicated, and the laboratory can play an important role in ensuring proper antimicrobial stewardship.

MLM: What standards might be applied to an effective influenza and COVID-19 management plan in the laboratory?

Zabaleta: Obviously, very few standards can be applied to a COVID-19/influenza testing program given the conditions that all hospitals and laboratories find themselves in today. We remain in a pandemic and it is not back to business as usual in any regard. With the constantly shifting supply chain for reagents, disposables, and instrumentation, most laboratories are left to cobble together whatever combination of platforms, POCT supplies, reagents, and disposables they can find.

That said, in what would be considered a normal situation, we would seek standardization via one or two platforms that meet our clinical needs and evaluate and implement those platforms to support our physicians. In this pandemic environment, the situation is more about how much reagent supply can be allocated by your vendors to support whatever instrumentation you have in place. Furthermore, most laboratories in the country have struggled to satisfy all their testing needs using one vendor or one platform, or even combinations thereof. In order to stay competitive against this virus, we need to validate multiple platforms and reagents so we can maintain steady COVID-19 testing by switching instrumentation according to the available reagent supply. This is definitely not business as usual.

MLM: If a laboratory has multiple platforms and different reagents, where and when are they utilized?

Zabaleta: Good question. The various health care environments within a typical hospital (ie, inpatient, ED, outpatient, presurgical testing, etc) have different needs, but traditionally, the laboratory has been able to meet their needs with one or two platforms (eg, POCT and central lab). However, in the COVID-19 pandemic we cannot afford to be so structured; we need to test and provide results in a timely manner according to individual environments.

  • In the urgent care setting, a POCT platform is preferable given the likelihood of testing symptomatic patients.
  • In the hospital ED, rapid testing either by POCT or “on-demand” type platforms is preferable. In this environment you are testing symptomatic and asymptomatic patients that will be admitted. Rapid throughput of ED patients is paramount.
  • For elective procedures testing or PAT, a high-throughput chemistry/immunoassay instrument in a centralized location is likely best. However, a reasonable TAT must be maintained. In the event of a positive test, an elective procedure would be rescheduled or cancelled. Further to this, patient scheduling must be taken into account, such that the health system can seek to contain costs associated with a cancelled procedure.
  • For symptomatic outpatients that will go home and self-quarantine, the option is available to send the samples to a central location in your system for testing, if you can provide a reasonable TAT or perform rapid testing. In this case, it is important to work with your medical staff to ensure a steady supply of reagents.

MLM: Now that vaccines for COVID-19 are being deployed, what trends do you expect regarding influenza, RSV, common cold?

Zabaleta: Social distancing and masks are most certainly helping to keep the number of flu, RSV, and common cold cases down, yet these numbers are expected to increase again in the future without masks and social distancing, and with some of the basic hygienic practices we have been promoting (hand washing, limited face touching) falling back to pre-pandemic rates. Hopefully, people will carry over some of these more basic measures that substantially decrease the spread of infectious diseases. While no one wants to continue wearing masks forever, things like hand washing, avoiding touching of the face (particularly during traditional flu season), and basic hygiene will help reduce the effects of flu, RSV, common cold and COVID-19.

Some of the questions moving forward will be, how long does immunity to SARS-CoV-2 last after a dual inoculation and how will regular vaccination for coronavirus be incorporated into general lab testing (eg, part of a normal respiratory testing panel)? Unfortunately, given what we have seen in the last 12-15 months, I think we will be obligated to manage the SARS-CoV-2 virus for the foreseeable future. 


  1. US Centers for Disease Control and Prevention. Similarities and Differences between Flu and COVID-19. Accessed 1.20.21:
  2. US CDC. Clostridioides difficile in COVID-19 Patients, Detroit, Michigan, USA, March-April 2020. Emerg Infect Dis. 2020;26(9):2272-2274. Accessed 1.20.21:

Eugenio H. Zabaleta, PhD, is a clinical chemist at OhioHealth Mansfield Hospital in Mansfield, Ohio. He is also a part-time lecturer at Cleveland State University’s graduate clinical chemistry program. He graduated from the Catholic University of Cordoba (Argentina) with a degree in biochemistry and received his PhD in chemistry from the University of Akron. His training in clinical pathology was at the Hospital Provincial San Roque in Cordoba. In Argentina, he was the laboratory medical director at the Clinica del Sol, a clinic devoted to mother and child’s care, with neonatology intensive care service.

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