COVID-19 vs. Flu: What's the difference?
Flu season is coming and COVID-19 is already here. You already know some important things you can do to stay healthy this year.
But do you know how to tell the difference between the two illnesses if you start feeling sick?
We’re here to help you better understand flu and COVID-19 so that you can make a plan for what to do if you start feeling sick.
What we know about the 2020 flu season so far
Flu season in Alabama usually begins in November and can last until early May. But flu season in the southern hemisphere usually peaks from June to August. Scientists use data from the flu season in the southern hemisphere to make predictions about the flu season in the northern hemisphere. This data helps us predict which strains of influenza to protect against in our flu vaccines as well as to predict how severe the coming flu season will be.
But the data for 2020 isn’t there. While many countries in the southern hemisphere were concerned about the threat of both COVID-19 and flu, flu simply was not present for the 2020 season. Many surveillance sites in the southern hemisphere reported that they collected fewer flu samples than they have ever collected since their labs or centers started.1
At flu surveillance sites in Argentina, Chile, Australia, and South Africa, the flu was virtually nonexistent. Each of the four countries reported fewer than 100 cases of the flu, and in South Africa, only 6 cases were reported.2 There are many possible reasons for this.
- People may have avoided medical treatment or testing because they were afraid of contracting COVID-19 at a clinic or doctor’s office
- Many clinics may have been closed due to shutdowns related to COVID-19
- Strategies used to mitigate the spread of COVID-19 (such as social distancing and more frequent hand washing) may have led to a significant decrease in community spread of the flu.
While we can make guesses about why there was so little flu in the southern hemisphere this year, there’s no way to know for sure. This makes the 2020 flu season in Alabama more unpredictable than ever.
Symptoms of Flu and COVID-19
Flu and COVID-19 are both viruses, but they are structurally different viruses. They also differ in their severity and in how they spread. But both flu and COVID-19 are classified as influenza-like illnesses (ILI). There are many influenza-like illnesses that circulate in any given year. ILIs are spread through respiratory droplets, share the same basic upper respiratory symptoms, and also share the same basic systemic symptoms.
Upper respiratory symptoms that are common in ILIs include a sore throat, sinus drainage, and cough. Common systemic symptoms for influenza-like illnesses include fever, chills, fatigue, and body aches. Whether you are infected with the flu, COVID-19, or some other influenza-like illness, there will be an overlap in the symptoms and it can be hard to distinguish between them based on symptoms alone.
There are also some important differences in the symptoms of influenza and COVID-19. The flu has a quicker onset with more severe symptoms. With flu, you can go from feeling fine to full-blown symptoms in 24-48 hours. COVID-19 usually begins with a low-grade fever that smolders for several days before other symptoms develop. Typical flu infections have symptoms that seem to appear suddenly but resolve more quickly (within about two weeks) than COVID-19, which can take much longer to resolve.
Why testing for COVID-19 and flu is important
In years past, it has been helpful - but not essential - to get tested for the flu. But in the context of the COVID-19 pandemic, it is critical for all patients to get tested test for the cause of your acute respiratory illness or ILI. Understanding the cause of your illness will help you know how to best treat your illness and mitigate its spread.
All influenza-like illnesses require similar supportive treatments such as rest, symptom control, and hydration. But prescriptions to treat your illness will be very different depending on the cause of your illness.
The most important reason to get tested for your influenza-like illness is so that you can know what to do to mitigate its spread. It’s no longer safe to simply assume you have the flu. Rapid-turnaround testing is necessary to distinguish between influenza, COVID-19, and other influenza-like illnesses.
Can you be infected with both COVID-19 and the flu?
Early in the COVID-19 pandemic in China, there were a few documented cases in which someone was infected with both COVID-19 and influenza. This coinfection was unusual and not widespread. But coinfection is still possible, so it makes getting your flu shot in 2020 more important than ever.
Flu and COVID-19 infections will deplete your immune system of many of the cells that are required to fight off other infections. But scientists are also considering whether or not infection with either flu or COVID-19 makes you more susceptible to getting the other. While the data is still unclear, it is still important to get your flu shot this year, especially since there is not yet an effective vaccine for COVID-19.
What should I do if I get sick?
If you get sick with fever and upper respiratory symptoms, you should get tested to find out the cause of your illness. It’s not enough to simply know if you’ve been infected with COVID-19; you need to get tested for other illnesses such as flu and other types of infections that are circulating in the community. Knowing the cause of your illness will help you know how to best treat your illness as well as keep from giving it to others.
1WHO Influenza update - 377. (2020, October 02). Retrieved October 09, 2020, from https://www.who.int/influenza/...
2Kelly Servick (2020, August 14). How will COVID-19 affect the coming flu season? Scientists struggle for clues. Retrieved October 09, 2020, from https://www.sciencemag.org/new...