COVID-19 and Influenza: What’s Different and What’s the Same

Written By Patty Maynard

COVID-19 and flu (influenza) are both viral respiratory infections that can have similar symptoms.  When both flu and COVID-19 are widespread in the community, testing will often be needed to tell them apart.  However, COVID-19 and flu do have some important differences.

Below we review what’s the same and what’s different when it comes to COVID-19 and the flu.  Each section will include key questions that are answered by a comparison graph. 

Symptoms 

  • Are there any symptoms that are more common with COVID-19?

  • How long after exposure do symptoms start with COVID-19 as compared to the flu?

2021-01-15_8-21-50.png

Key Points 

  • COVID-19 is suggested by a longer time from exposure to symptom onset and by loss of taste and smell. 

  • Although less common, loss of taste and smell can happen with the flu. 

 How it Is Spread

  • Can people spread both COVID-19 and the flu (contagious) before they have any symptoms? 

2021-01-15_8-22-38.png

Key Points 

  • A person with COVID-19 can spread the illness for a longer period of time than the flu. 

  • Both COVID-19 and flu can be spread by people that do not have any symptoms (i.e., asymptomatic).

Complications

  • Are there differences in the complications of COVID-19 versus the flu?

2021-01-15_8-18-04.png

Key Points 

  • Death rate is higher in COVID-19 than seasonal flu (at least 10 times higher).  COVID-19 is associated with MIS-C and may increase blood clots. 

  • Severe complications often start later in COVID-19 compared to the flu. 

High Risk Groups

  • Are young healthy children at higher or lower risk of complications from the flu compared to COVID-19?

  • What other groups are at higher risk?

2021-01-15_8-18-59.png

Key Points 

  • The elderly and those with chronic health conditions are at high risk for complications from both illnesses. 

  • Healthy young children have a lower risk of complications from COVID-19 compared to the flu.  However, children with chronic health conditions are at high risk for COVID-19 complications.  

Treatment and Prevention  

  • Does physical distancing work for both flu and COVID-19?

2021-01-15_8-20-16.png

Key Points 

  • Get the flu vaccine!

  • Get the COVID-19 vaccine when it becomes available! 

  • Physical distancing, hand hygiene and using masks can help prevent both illnesses.

Some Final Thoughts

  • Remember that people can become ill with BOTH COVID-19 and other respiratory infections at the same time, including flu (i.e., coinfection).

  • Triagers should use their clinical judgment, but generally will want to use the COVID-19 Diagnosed or Suspected guideline when a patient calls with typical COVID-19 symptoms and there is community spread.

  • During the 2020-2021 influenza season, triagers can use the COVID-19 Diagnosed or Suspected guideline.  We have included triage questions related to influenza as part of this updated COVID-19 guideline. 

  • An exception would be the patient who has flu-like symptoms and has had a definite close exposure to someone with influenza (flu test positive).  In this case use the Influenza guideline.

  • COVID-19 is still a new illness.  Our understanding of symptoms, complications and treatment are changing rapidly.  Good sources of up-to-date information includes the Centers for Disease Control and Prevention (https://www.cdc.gov) and the World Health Organization (https://www.who.int/).

Author

Gary Marks, DO

Medical Editor, Clinical Informaticist, Adult Clinical Content

Schmitt-Thompson Clinical Content, LLC

Co-Authors

Cheryl Patterson, RNC-TNP, BSN

Nurse Editor, Adult Clinical Content

Schmitt-Thompson Clinical Content, LLC

David Thompson, MD

Senior Medical Editor

Schmitt-Thompson Clinical Content, LLC

References

  • Butowt R, von Bartheld CS. Anosmia in COVID-19: Underlying Mechanisms and Assessment of an Olfactory Route to Brain Infection. Neuroscientist. 2020 Sep. 

  • Ding Q, Lu P, Fan Y, Xia Y, Liu M. The clinical characteristics of pneumonia patients coinfected with 2019 novel coronavirus and influenza virus in Wuhan, China. J Med Virol. 2020 Mar 20:10.

  • Ives-Tallman C, Guest B. Novel Coronavirus 2019 (COVID-19).  EmRAP CorPendium.  Updated: October 27, 2020.

  • Tenforde MW, Kim SS, Lindsell CJ, et al. Symptom Duration and Risk Factors for Delayed Return to Usual Health Among Outpatients with COVID-19 in a Multistate Health Care Systems Network — United States, March–June 2020. MMWR Morb Mortal Wkly Rep 2020;69:993-998.

Patty Maynard
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