Evidence Suggests Similarities and Differences Between COVID19 and the Flu

By Consultantsreview Team Wednesday, 03 March 2021

Evidence Suggests Similarities and Differences Between COVID19 and the FluCOVID19 is caused by the novel coronavirus SARS-CoV-2, and the flu is caused by influenza viruses that work in a similar way, so it’s no surprise that evidence suggests some of the symptoms that patients might experience with both illnesses can overlap. Feeling feverish and dealing with a cough are common symptoms of both the flu and COVID19, so it can sometimes be hard to tell which one a patient has got if they are experiencing symptoms. However, there are some key differences between COVID19 and the flu that are worth knowing about. The only way to tell for sure whether it is COVID19 or the flu is to get tested for COVID19 but understanding how they are similar and how they differ can also help. 


When it comes to COVID vs Flu, there are several similar symptoms that a patient might experience. These include feeling feverish, a cough, fatigue, a sore throat, a runny or stuffy nose, headaches, muscle aches, and shortness of breath.


Both COVID19 and the flu can make a person feel ill and run-down. However, the illnesses that the two types of viruses may cause can differ. Flu viruses can cause mild to severe illness, depending on a number of factors including the type of virus and the patient’s current health condition. COVID19, on the other hand, appears to cause more serious illnesses in some patients.


Both COVID19 and the flu are similar in terms of when symptoms can appear, with one or more days passing before a person starts to experience symptoms after becoming infected. However, with COVID19, it can often take longer for the patient to develop symptoms compared to the flu. With the flu, people will typically develop symptoms around 1-4 days after infection, while COVID19 symptoms tend to appear no sooner than five days after being infected, although this can range from 2-14 days.

Rate of Infection:

With both the flu and COVID19, people can spread the virus to others for at least one day before they have experienced any symptoms. However, if the patient is infected with COVID19, they may be contagious for a longer period of time compared to somebody with the flu. Adults and older children with the flu are typically at their most contagious for the first three to four days but can remain contagious for up to a week. With COVID19, while the exact rate of infection is still under investigation, it is possible for infected people to spread the virus for at least ten days after experiencing symptoms. Some people may also be asymptomatic with COVID19, yet still able to spread the virus to others.

How it Spreads:

Both the flu and COVID19 are spread from person to person by the droplets made when they talk, cough or sneeze. It is possible to become infected with either virus by touching something that is contaminated with the virus before touching the face. However, COVID19 has been observed to have more superspreading events compared to the flu, and can spread among people much faster and easier.

While it might take a test to know for sure if a person has COVID19 or the flu, understanding the similarities and differences can help a patient determine where their symptoms might be coming from. 

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