Covid, Flu Or RSV Symptoms? Here's How To Tell The Difference

It can be pretty hard to tell these circulating viruses apart, but experts share how to decipher them.
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Three respiratory viruses are still circling at a high rate right now — flu, Covid-19 and RSV (or respiratory syncytial virus).

These viruses have similar symptoms in most healthy adults but can impact certain populations (children, older adults or immunocompromised people) more severely. Also, it can be helpful, in general, to know what virus you’re dealing with for your peace of mind.

Unfortunately, there isn’t a surefire way to tell these viruses apart (aside from testing, which isn’t always available). But some telltale signs can help you glean what you’re dealing with. Here, experts share signs to look for to determine which virus you have.

First, severe RSV is most common in children and immunocompromised adults

As Dr. Laolu Fayanju, regional medical director at Oak Street Health in Ohio, explains, RSV generally infects children. And nearly all children get RSV by the age of two.

So, if you’re dealing with sick infants and young toddlers, there’s a higher chance that their infection is RSV compared to other populations. “This child will usually present with a runny nose [and] fever,” he said.

While symptoms like a runny nose or low fever aren’t enough to bring your child to their pediatrician, another sign of RSV – trouble breathing – is a reason to go, adds Dr. Vandana Madhavan, clinical director of Paediatric Infectious Disease at Mass General for Children.

“If you’re noticing your child is working harder to breathe ... [or] if you’re noticing they’re not drinking as much, those are all signs the baby needs to come in,” Madhavan said.

If you don’t notice those symptoms, your child likely does not need to go to the doctor, and you can instead call to talk to your pediatrician about virus management.

Madhavan noted that doctor’s offices are overrun right now, and if you bring your child in for mild symptoms that would otherwise get better at home, there’s a chance they could pick up another illness while at the doctor.

Also, adults with certain chronic conditions are at risk of severe RSV, particularly “older people with chronic lung diseases,” Fayanju says.

Gastrointestinal issues are not generally associated with RSV

If you have RSV, it’s unlikely that you will experience gastrointestinal issues, say both Fayanju and Madhavan. These side effects are typical of a Covid-19 infection, which can cause vomiting and diarrhoea.

Flu can also cause vomiting and diarrhoea, Madhavan notes. But, keep in mind that this is much more common in children than adults, according to the US Centers for Disease Control and Prevention (CDC). Most adults with the flu won’t have gastrointestinal issues.

Loss of taste and smell is most common during a Covid-19 infection

A loss of taste and smell is one way to distinguish Covid-19 from the flu and RSV, Fayanju says, although that symptom is less common now than it was in the earlier days of the pandemic.

This isn’t the same as the loss of taste and smell from congestion. The loss of taste and smell with a Covid-19 infection generally happens pretty early on as one of the first signs of the virus ― sometimes even with no other symptoms, according to the Cleveland Clinic.

Madhavan says there is no guarantee that you’ll have this side effect even if you have Covid-19, but if you do, it’s likely a sign of the virus and not the flu or RSV.

Lasting symptoms are usually a sign of Covid-19

“Unlike flu and RSV, Covid appears to have lingering long-term effects, ” commonly known as long Covid, Fayanju says.

This can include brain fog or confusion after the infection clears up or a loss of taste and smell that doesn’t return for weeks. But, similar to above, not all Covid infections will lead to long Covid (and a new study says by taking the antiviral Paxlovid, you can reduce your risk of developing the condition).

It’s less common for flu and RSV to result in long-term symptoms, but studies show that RSV can cause long-term wheezing after infection.

Additionally, Fayanju notes that flu can “lower the body’s natural defenses” and cause “an inflammation cascade that can set off other diseases, mainly heart attacks [and] strokes, especially in adults.” Covid-19 also results in higher levels of inflammation in the body post-infection that puts you at risk for stroke, heart attack and more.

This underscores the importance of getting your seasonal flu vaccine and Covid shots.

One way to tell what virus you have is by taking a Covid test — tests for RSV and flu are available, too, but Covid tests are the most readily available.
Carol Yepes via Getty Images
One way to tell what virus you have is by taking a Covid test — tests for RSV and flu are available, too, but Covid tests are the most readily available.

Keep in mind that you could also have two infections at once

In news no one wants to hear, it’s also possible to catch two infections at the same time, according to Madhavan. Especially during times of high virus spread, like right now.

“You might not catch them both at the same time, but you might have cough and cold symptoms and then develop a fever, and it might not be the evolution of that original set of symptoms,” she says. “It might be that you have two infections going on.”

Last winter, the term “flurona” grew in popularity as Omicron and flu cases surged throughout the country. Some people were infected with both viruses at the same time.

“It is true that when you’re infected, your immune system is under attack. Therefore your immune defences are weakened. And therefore your ability to defend against another infection is reduced,” David Edwards, an aerosol scientist, faculty member at Harvard University, and inventor of FEND, a nasal mist that aims to trap and flush out tiny pathogens, previously told HuffPost.

So, as your body fights off one infection, it is also more susceptible to others.

Overall, it’s hard to tell the difference between these viruses based on singular symptoms

I think the point to emphasise is that there is so much overlap in symptoms among the three,” Madhavan says. “They’re all primarily respiratory viruses.”

She notes that the flu and RSV could resemble an upper respiratory tract infection or a common cold in healthy adults. Covid can also present like this in people who are fully vaccinated against the virus.

And, just because you have a specific virus doesn’t mean you’ll have the same symptoms as someone else — your Covid infection could come with a bad cough, while your partner’s Covid infection may present as fever and fatigue.

Both Madhavan and Fayanju note that Covid-19 at-home tests are easy to come by; you can buy them from your local pharmacy or order them online from retailers like Amazon. If you test positive for Covid, you should alert anyone you recently came in contact with, Madhavan adds.

Follow health precautions to lower your risk of getting sick

“Continue to take all of these viruses very, very seriously,” Fayanju says, who adds that with holiday season coming, there will be more “travelling and gathering,” which means more chances for virus spread.

It’s important to think about lowering your risk – stay home if you’re sick, wash your hands, wear a mask in crowded spaces, and get vaccinated for Covid-19 and the seasonal flu, he says. Through these measures, Fayanju adds, we can “keep people well and out of the hospital through the holidays.”

Experts are still learning about Covid-19. The information in this story is what was known or available at the time of publication, but guidance could change as scientists discover more about the virus. To keep up to date with health advice and cases in your area, visit and

Lynn Scurfield for Huffpost

Winter calls for us to take greater care of ourselves and each other, from our health and homes to our headspace and matters of the heart. Whether you’re seeking motivation or hibernation, HuffPost UK’s Winter Well series is here to help you through the short days and the longer months.