Difference Between COVID-19, Influenza, and Colds

Difference Between COVID-19, Influenza, and the Common Cold

The emergence of coronavirus disease 2019 or COVID-19 caused by the SARS-CoV-2 in December 2019 in China and the subsequent global outbreak beginning in January 2020 have raised another concern: how is it different from influenza or flu and the common cold?

Remember that COVID-19 is caused by a type of coronavirus now called SARS-CoV-2 that is similar to SARS-CoV that first emerged in 2002. On the other hand, influenza is caused by the influenza virus, which includes different genera and strains.

The common cold is a general term for an upper respiratory infection caused by a virus. There are over 200 viruses that have been associated with this disease, including the rhinovirus, influenza viruses, and human coronavirus.

Understanding the Similarities and Differences Between COVID-19, Influenza, and the Common Cold

For starters, these three are viral infectious diseases primarily affecting the respiratory system. Some of the signs and symptoms are almost similar. The World Health Organization also noted that both COVID-19 and influenza have a similar disease presentation, thereby making diagnosis essential to provide proper treatment.

The following are the signs and symptoms common among the three:

• All three are often accompanied by respiratory distress, especially dry cough in earlier stages, and in later stages, mucus build-up in the lungs. Remember that these three are primarily respiratory illnesses.

• Other symptoms shared by these three include fatigue, muscle ache or body pains, headache, and loss of appetite. It is difficult to distinguish between the common cold, influenza, and COVID-19 at the early stages of the infections.

• There is a need for a proper diagnosis because the overall clinical presentation is similar. Remember that determining the exact cause of respiratory distress is important to provide the necessary treatment.

• Some infected individuals exhibit no clinical presentation. Hence, they can also be asymptomatic, and affected patients can be carriers of the involved infections despite experiencing no signs and symptoms.

However, there are still considerable differences between the three. Note that the common cold is primarily a viral disease of the upper respiratory tract, thus primarily exhibiting upper respiratory symptoms such as sneezing, runny nose, nasal congestion, and/or sore throat.

The grave concern over influenza and COVID-19 comes from the fact that they affect the lower respiratory tract, thus causing shortness of breath or difficulty in breathing, severe mucus build-up, and chest pain in advanced stages.

Some cases of coronavirus disease and the flu can also result in gastroenteritis, thus resulting in vomiting and diarrhea. Both can be deadly as well as the involved viruses and systemic response of the body result in more serious complications.

Below are the complications of COVID-19 and influenza:

• Both diseases can result in viral pneumonia that, in turn, can result in acute respiratory distress syndrome or ARDS. Note than an ARDS is a type of respiratory failure caused by the rapid onset of widespread inflammation of lungs.

• Sings and symptoms of ARDS shortness of breath, rapid breathing, and bluish skin coloration. The condition is fatal. Most patients who survive this disease exhibit a considerable decrease in quality of life.

• Patients who survive severe cases of either COVID-19 or influenza can also exhibit lesions in their lungs. Remember that the involved virus attacks the lungs. However, the innate immune response worsens the severity of lung injury.

• Both COVID-19 and influenza can progress further to sepsis, which is an extreme reaction of the body to infections that causes injury to tissues and organs, thus resulting in multiple-organ failure if left untreated.

• Symptoms of sepsis include high-grade fever, rapid heart rate, shivering or feeling very cold, extreme pain or discomfort, and confusion or disorientation.

Additional Notes and Facts about the Similarities and Differences Between COVID-19, Influenza, and the Common Cold

The onset of the common cold usually starts two to three days upon exposure to the involved virus. This is generally the same for influenza. On the other hand, research has revealed that the onset for COVID-19 can take between two to 14 days from exposure.

It is also important to highlight the fact that the common cold is a mild respiratory infection. The majority of COVID-19 and influenza cases are also mild, while some are asymptomatic. However, people with mild or asymptomatic cases of coronavirus disease or flu are still considered infectious and able to transmit the disease person-to-person.

With regard to the route of infection and mode of transmission, the viruses involving the three can be transmitted via airborne droplets, direct contact with contaminated nasal secretions, and contact with contaminated objects.

Remember that both COVID-19 and influenza can still exhibit upper respiratory symptoms such as runny nose, nasal congestion, and/or sore throat. This is the reason why it is important to get a proper diagnosis to receive proper treatment and prevent an outbreak.


  • Duszynski, T. 2020, March 9. “Coronavirus and Flu: Why COVID-19 Poses More of a Threat.” Agenda. The World Economic Forum. Available online
  • Herold, S., Becker, C., Ridge, K. M., and Budinger, G. R. S. 2015. “Influenza Virus-Induced Lung Injury: Pathogenesis and Implications for Treatment.” European Respiratory Journal. 45(5): 1463–1478. DOI: 1183/09031936.00186214
  • Lauer, S. A., Grantz, K. H., Bi, Q., Jones, F. K., Zheng, Q., Meredith, H. R., Azman, A. S., Reich, N. G., & Lessler, J. 2020. “The Incubation Period of Coronavirus Disease From Publicly Reported Confirmed Cases: Estimation and Application.” Annals of Internal Medicine. DOI: 7326/M20-0504
  • Livingston, E., Bucher, K., & Rekito, A. 2020. “Coronavirus Disease 2019 and Influenza. JAMA.” DOI: 1001/jama.2020.2633
  • Maragakis, L. L. 2020. “Coronavirus Disease 2019 vs. the Flu.” Health. John Hopkins Medicine. Available online
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