While they’re caused by two different viruses, COVID-19 and the flu are both contagious respiratory illnesses which present very similar symptoms. But if you’re experiencing a cough or fever during cold and flu season, how can you tell if it’s the flu vs COVID? . Here, find out about a new at-home test that might be able to tell the difference, plus learn doctors’ tips for distinguishing between COVID-19 and the flu.
The flu vs. COVID: Symptoms that overlap
COVID-19 is caused by a coronavirus (SARS-CoV-2) infection, while the flu stems from influenza virus. According to the CDC, both illnesses cause varying severity of symptoms. The most common shared symptoms include:
- Fever or feeling feverish
- Chills
- Cough
- Shortness of breath or difficulty breathing
- Fatigue
- Sore throat
- Runny or stuffy nose
- Muscle pain or body aches
- Headache
- Vomiting
- Diarrhea (more frequent in children with flu, but can occur in any age with COVID-19)
- Change in or loss of taste or smell (more common with COVID-19)
The flu vs COVID: Symptoms that differ
A University of Southern California study from 2020 suggests that COVID-19 symptoms may appear in a specific order.
The authors analyzed symptom data from the World Health Organization (WHO) for over 56,000 confirmed COVID-19 cases in China. They also examined data from over 2,400 reported cases of the flu in North America, Europe and the Southern Hemisphere between 1994 and 1998. They found thatCOVID-19 symptoms often appear in this order:
- Fever
- Cough and muscle pain
- Nausea or vomiting
- Diarrhea
On the other hand, researchers said flu symptoms often begin with a dry cough that could eventually lead to fever, chills and body aches.
How to tell if it’s the flu vs COVID
Doctors say professional testing is really the only way to know definitively whether you have COVID-19 or the flu, as there is no absolute method for diagnosing based on symptoms alone.
“While these [study] insights may be helpful, functionally there is enough symptom overlap that it is exceedingly challenging to guess which virus someone has based on symptoms with respect to flu versus COVID-19 versus many other respiratory illnesses,” explains Scott Roberts, MD, Associate Professor of Infectious Diseases at Yale School of Medicine.
Fever and cough are two of the most common symptoms for both, he says, so it’s not advisable to rule out a diagnosis of one based on the order symptoms appear. In general, any respiratory viral symptoms should prompt consideration for both COVID-19 and the flu.
Raj Dasgupta, MD, Chief Medical Advisor for Garage Gym Reviews, says in his clinical experience, people infected with SARS-CoV-2 may take longer to show symptoms and may be contagious for longer periods of time than those infected with the influenza virus.
Still, he emphasizes that testing is necessary to confirm a diagnosis of COVID, the flu or, in rare cases, both at the same time.
A new combined flu and COVID at-home test now available
While scheduling a visit with your doctor typically provides the most accurate diagnosis, there’s also a new way to uncover what’s causing your symptoms. Both doctors we spoke to point to a new at-home test for both COVID-19 and the flu as a potential diagnostic tool. In October, the Food And Drug Administration (FDA) approved the Healgen Rapid Check COVID-19/Flu A&B Antigen Test for public use.
The test is available over the counter at most pharmacies and uses a nasal swab sample to provide results in approximately 15 minutes for COVID-19 and flu by detecting proteins from both.
How effective is it? The FDA reviewed data from a study of individuals with symptoms of COVID-19 and influenza. The study results showed that this test correctly identified 99 percent of negative and 92 percent of positive SARS-CoV-2 samples, 99.9 percent of negative Flu A and B samples and 92.5 percent and 90.5 percent of positive Flu A and Flu B samples, respectively.
Why it’s important to know if you have the flu vs COVID
Whether you test yourself or are diagnosed by a medical professional, having a clear diagnosis is required for proper treatment and to avoid transmission (people with COVID-19 are believed to be contagious for longer periods).
“Having a test that detects both flu and COVID-19 allows you to get appropriately diagnosed and treated quickly,” says Dr. Dasgupta. “Getting treated early for COVID-19 and the flu can reduce your risk of getting very sick. Though uncommon, individuals can be infected with the flu and COVID-19 at the same time. This can result in a more severe illness than people with either flu or COVID-19 alone.”
Additionally, the flu and COVID have unique treatments, so it matters which virus is present, notes Dr. Roberts. While most people with the flu won’t need medical care, some may require an antiviral drug such as Tamiflu. This should be started as soon as possible and can help shorten the duration you’re sick, the CDC reports. To treat COVID-19, doctors may prescribe those at risk of severe illness (like adults over age 65) an antiviral such as Paxlovid.
This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan.
