COVID-19 has taken center stage in terms of public health policy since its introduction to humans in late 2019. The vast media coverage and government advice surrounding COVID-19 makes it easy to forget that SARS-CoV-2 is just one of many commonly circulating respiratory viruses. These viruses have a similar pathology, and therefore, many overlapping symptoms, making it impossible to define the infection based on symptoms alone. Let's look at both the shared and unique characteristics of these common causes of cold and flu-like symptoms, and why diagnostic testing is essential to dictate effective treatment.

The Flu is caused by seasonal influenza virus infection, with cases peaking between December and February1. The symptoms of an influenza infection, as per the Centers for Disease Control and Prevention (CDC) guidelines, include: fever or chills, cough, fatigue, body aches, headache, sore throat, congestion or runny nose, vomiting, and diarrhea1. Flu shares many characteristics with other respiratory viruses including rhinovirus, respiratory syncytial virus (RSV), and SARS-CoV-2, making it very difficult to pinpoint which infectious pathogen is present. In severe cases, the CDC currently recommends the use of 4 FDA-approved antiviral drugs for flu treatment: oseltamivir, zanamivir, peramivir and baloxavir marboxil 2.

COVID-19 presentation is highly variable and can be asymptomatic in nature, mild cold-like symptoms, or severe illness requiring hospitalization. Symptoms include all the aforementioned flu symptoms. In addition, there are several symptoms unique to COVID-19 that may help differentiate between the two infections in certain cases. These include shortness of breath, new loss of taste or smell, and nausea3. However, these unique symptoms are often not present, making diagnostic testing the only means to accurately define the infection3. Current COVID-19 prevention is largely reliant on vaccination; however, therapies to fight an active infection are continually being developed and include FDA-emergency use authorization of monoclonal antibodies (sotrovimab) and the antiviral drugs Remdesivir, Paxlovid, Molnupiravir 4.

The Common Cold is the most prevalent viral illness and is caused by not one, but many different respiratory viruses that all elicit similar symptoms. Rhinovirus infection is the most common cause of a cold, but others include RSV, human parainfluenza viruses, adenovirus, common human coronaviruses, and human metapneumovirus5. Many common cold symptoms are shared with the flu and COVID-19, including a sore throat, runny nose, coughing, headaches, body aches, and in particular relation to COVID-19, the possibility of loss of smell. However, diarrhea, nausea and vomiting almost never occur6. Sneezing is one symptom of the common cold that is rare in flu and COVID-19. RSV infection accounts for about 20% of common-cold illnesses7, and while cold symptoms are usually mild and begin in stages, RSV can cause more severe illnesses, such as bronchiolitis and pneumonia8.

Allergies are another cause of cold-like symptoms that can often be confused as a viral infection due to their ability to cause rhinitis – inflammation of the nose9. Treatment for allergic rhinitis includes antihistamines, decongestants, nasal corticosteroids, and leukotriene receptor antagonists.

Pandemic Response Lab Provides the Solution

It’s clear from the similarity of illness that differentiating between each type of viral infection or allergic reaction is not possible based on symptoms alone. The CDC states that diagnostic testing may be required to confirm a diagnosis for respiratory infection3. We have also highlighted how varied the treatment course is for each cause of cold-like symptoms, ranging from monoclonal antibodies, many different types of antivirals or antihistamines, and therefore, precise diagnosis of the infectious pathogen is critical for correct treatment. 

To help clinicians and better inform treatment decisions, Pandemic Response Lab (PRL) has developed a concise respiratory panel, which simultaneously tests for SARS-CoV-2, influenza A and B, and RSV. Utilizing in-house automation and diagnostic expertise, PRL offers this multi-target panel at a price lower than the cost of many COVID-only PCR tests available. PRL’s proprietary innovations in automation and sample processing enable high assay sensitivity and specificity, with a turnaround time as quick as 24 hours, to help ensure fast and accurate diagnoses. To better suit the needs and preferences of patients, PRL can also accept several sample types, including saliva and nasopharyngeal or anterior nares swabs.* For more information on how PRL can meet your diagnostic testing needs, contact us today.



        1. Flu Season | CDC. Published September 29, 2021. Accessed April 3, 2022.
        2. CDC. What You Should Know about Flu Antiviral Drugs. Centers for Disease Control and Prevention. Published August 31, 2021. Accessed April 3, 2022.
        3. CDC. Coronavirus Disease 2019 (COVID-19) – Symptoms. Centers for Disease Control and Prevention. Published March 22, 2022. Accessed April 3, 2022.
        4. What Clinicians Need to Know About the New Oral Antiviral Medications for COVID-19. :80.
        5. CDC. Common Colds. Centers for Disease Control and Prevention. Published November 29, 2021. Accessed April 3, 2022.
        6. COVID-19, cold, allergies and the flu: What are the differences? - Mayo Clinic. Accessed April 3, 2022.
        7. Causes of the Common Cold. WebMD. Accessed April 3, 2022.
        8. CDC. Symptoms and Care for RSV. Centers for Disease Control and Prevention. Published December 18, 2020. Accessed April 3, 2022.
        9. Allergens and Pollen | CDC. Published December 21, 2020. Accessed April 3, 2022.
        10. Sneezing and Sniffling: How to Tell If It’s Allergies or a Cold | Asthma and Allergy Foundation of America. Accessed April 3, 2022.

          *Accepted sample types for the PRL Concise Respiratory Panel are lab dependent. Tests run in each PRL laboratory are independently developed and validated at their respective facility; performance of tests may vary. 


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COVID, the Flu, or the Common Cold? How to Differentiate Between Respiratory Infections with Similar Symptoms

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