COVID-19 VS. the Flu

Published: April 6, 2020
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Category: Blog

How the two viruses vary and why the differences matter

Have your discussions with family and friends regarding the Coronavirus promoted the question, “What’s the big deal – isn’t COVID-19 just like the flu?” Many comparisons have been drawn between the two viruses that cause respiratory disease, but there are important differences between them. Understanding how a virus spreads and what makes it unique plays a pivotal role in how we respond to it and prevent its expansion. Let’s take a look at how the Coronavirus and Influenza compare to better comprehend the measures we can take to protect ourselves from BOTH illnesses.

How are the Coronavirus and Influenza similar?

Two key ways that medical professionals assess viruses is to analyze how symptoms present themselves and how the viruses are transmitted. Both COVID-19 and the flu cause respiratory disease. Depending on the person who contracts either virus, symptoms can vary dramatically. Some people may never even know that they have contracted either virus and be completely asymptomatic, while others experience fever, sore throat, gastrointestinal issues, body aches, and a severe cough. Both illnesses, when contracted by high-risk patients, like the elderly, can result in death.

The Coronavirus and Influenza are both transmitted by direct contact with an infected person, respiratory droplets, and fomites (clothes, utensils, hard surfaces). For this reason, many of the ways that you protect yourself from contracting the Flu each year are also effective in preventing the spread of COVID-19. These measures include washing your hands frequently, coughing into your elbow, and disinfecting high traffic hard surfaces.

How are the Coronavirus and Influenza different?

A significant difference between these two viruses is the speed of transmission. If you have contracted the Flu before, especially if it has ever run its course through your family or classmates, you will have experienced a shorter incubation period for a virus. This means that you will present symptoms fairly quickly after the time of infection, around 1-4 days for the Flu. Besides having a shorter incubation period than the Coronavirus (up to 14 days), Influenza also has a shorter serial interval, or the time it takes a primary patient to infect a secondary patient. This means that the Flu, with an interval of about 3 days, can spread faster than COVID-19, which has an interval of around 5-6 days.

While this difference may initially sound like a positive, scientists are now finding that the Reproductive Number, or RO of COVID-19, is higher than the Flu. The RO of a virus refers to the number of secondary infections generated from one infected person. Even though Influenza spreads more quickly, its RO is estimated at around 1.3. The RO of the Coronavirus now appears to be about 2.5 or higher. This means that someone who has contracted COVID-19 may spread it to more people than if he or she was infected with the Flu.

Other key differences researchers are finding between COVID-19 and the Flu

  • Unlike the Flu, children seem to be less affected by the Coronavirus than adults. Preliminary data from household transmission studies in China suggest that most children are infected by adults in their homes.
  • The clinical attack rates of young people 19 years and younger is very low with COVID-19.
  • While new data suggests that around 80% of those infected with the Coronavirus have mild symptoms or are completely asymptomatic, 15% experience a severe infection that may require oxygen. 5% may be critical infections, even requiring ventilation. These severe and critical infection rates are higher than Influenza.
  • High-risk populations for the Flu are traditionally children, pregnant women, the elderly, and those with chronic medical conditions. For COVID-19, the highest risk populations seem to be the elderly and those with underlying conditions that increase their risk for severe infection.
  • Although time is needed to assess the exact mortality rate of the Coronavirus, it appears to be already higher than that of Influenza, especially Seasonal Influenza. Present data suggests that the Crude Mortality Ratio (the number of reported deaths divided by the number of reported cases) is 3-4%. We can assume that the Infection Mortality Rate (the number of reported deaths divided by the number of diagnosed infections) will be lower. However, mortality rates for Seasonal Influenza are usually well below 0.1%.
  • It is important to note that access to quality health care can have a significant impact on mortality rates.

*Stay up to date on the Coronavirus in Minnesota by visiting the Minnesota Department of Health information page. CLICK HERE

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