Editor’s Note: See cold and flu activity in your area with the WebMD tracker.
Nov. 17, 2022 — The overlapping symptoms of respiratory viruses with household names — COVID-19, the flu, the common cold, and RSV (respiratory syncytial virus) — can make it hard to tell them apart.
But how quickly symptoms appear, how long they last, and even which symptom(s) you have can be important clues. Some treatments are available and they work best when caught early, so it’s worth determining what infection is hitting you, a friend, or a loved one.
The American Academy of Pediatrics has a useful page explaining which symptoms are most likely with which respiratory diseases. “I think it’s a very good graph. And I think it’s basically the same for children and adults,” says Patricia (Patsy) A. Stinchfield, registered nurse and president of the National Foundation for Infectious Diseases (NFID).
One exception she proposed is that children with COVID-19 report less loss of taste and smell than adults.
“It is extremely, extremely difficult to differentiate our symptoms between influenza, RSV and COVID-19…for parents and physicians elsewhere,” says Mobeen Rathore, MD, member of the infectious diseases committee of the American Academy of Pediatrics.
Stinchfield agrees that these viruses cause many of the same symptoms, such as congestion, coughing and the potential for fever. But that doesn’t mean it’s impossible to tell them apart.
The fast and the furious
“After 44 years as an infectious disease nurse practitioner, one of the things I would ask people trying to figure out how sick they are is about the onset.” For both children and adults, the flu often breaks out very quickly. “It’s like a minute when a child is playing or an adult is working – and the next minute…it’s that feeling of being run over by a Mack truck.
In contrast, other viral illnesses tend to show up more slowly, she says. “People will say they feel like they have something, have chills, a sore throat, or feel ‘jaded’.”
Gastrointestinal symptoms can be another clue. Vomiting and diarrhea are more common with COVID-19, and to some extent influenza, compared to RSV. This happens in part because the COVID-19 virus attaches to ACE2 receptors found in both the lungs and the gut, so it can affect both parts of the body.
Additionally, it is well accepted that loss of taste and smell is a unique sign of COVID-19 infection. So it can help you distinguish COVID-19 from other viral illnesses.
Symptoms that point to RSV
More sneezing, “profuse amounts” of nasal mucus – snot – from a runny nose and wheezing are hallmark symptoms of RSV. Wheezing occurs when a child or adult whistles while breathing. Stinchfield says, “You don’t see as much wheezing in COVID or the flu as you do with RSV.”
“With RSV, it’s more of an upper respiratory infection, and people tend to have more of what we call bronchiolitis,” Rathore says. Bronchiolitis is inflammation and congestion of the small airways in the lungs, which in turn can cause wheezing.
Additionally, some people with RSV find it so difficult to breathe normally that they rely on other muscles to help them, including the muscles just above and below the breastbone.
The cold is still there
“People are talking a lot about RSV right now. – and rightly – but at least what we see is quite different,” Rathore says. The latest internal figures from the American Academy of Pediatrics’ Infectious Diseases Committee suggest that the common cold is the predominant virus at the moment, followed by influenza, RSV and COVID-19.
Rathore estimates that about 35% of patients with viral illness test positive for the rhinoenterovirus that causes the common cold.
“So it’s probably much more common than all the other infections we’re talking about,” he says. And yes, the common cold is more common, “but it’s also relatively less likely to cause more serious illnesses.”
Testing remains essential
Stinchfield shared two main messages. Tests are the only reliable way to diagnose a viral illness. “So if someone says, ‘It’s definitely RSV’ and your child hasn’t been tested, you really don’t know.”
It’s important to test very young children because they can’t describe their aches and pains, says Rathore, who is also chief of the division of pediatric infectious diseases and immunology at the University of Florida at Jacksonville.
The tests can also confirm the flu or COVID. “The good thing is that there are combination rapid tests that we use in clinics that can look at COVID-19, influenza and RSV all in one,” Stinchfield says. She hopes that similar combined home tests will be available in the future.
Another reason to test is “there is a treatment for COVID-19 and a treatment for the flu, so it’s important to know what you have so you can potentially benefit from early treatment.”
Stinchfield also says there are effective vaccines for COVID-19 and influenza, and a vaccine to protect against RSV is in development.
Don’t hesitate to get help
Trust your instincts if you feel a viral illness is getting worse, Stinchfield says. “Just listen to your instincts. If you’re scared, if you’re like, ‘This isn’t right,’ ‘my husband doesn’t look right,’ ‘my baby doesn’t look right,’ get some medical help.
“That’s what we’re here for,” she said.
Stinchfield acknowledges that there may be longer than usual wait times to see a pediatrician or infectious disease doctor due to the RSV outbreak. Also consider a virtual appointment if you’re concerned about exposure to others in a medical setting, she says.
Are we ready for a worrying winter?
With several notable viruses circulating, some experts warn of a “double outbreak” or “triple outbreak” this winter. Rathore went one step further. “I actually call it a possibility of a quaternary half.” In addition to COVID-19, RSV and influenza, the common cold virus is also prevalent.
In fact, in his area of Northeast Florida, RSV rates appear to be dropping, the flu is on the rise, and with COVID-19, “there is concern that it will come back like it has in previous seasons.” At the same time, rates of the common cold are holding up.
“There’s nothing you can say for sure ‘about which viruses will dominate over the coming winter,’ Rathore says. But the flu season in the southern hemisphere has been relatively severe, and that often predicts what is happening in the United States and other parts of the northern hemisphere, he says.
On a positive note, last season’s flu shot was a good match to protect against the flu strain that has been circulating in Australia and elsewhere, which might be reassuring here. “So that’s all the more reason for everyone who is eligible for the flu vaccine to get it.”