With a potential "tripledemic" of respiratory viruses this winter, health experts are offering tips to help people differentiate between Covid-19, flu, and respiratory syncytial virus (RSV), as well as tips to avoid getting sick in the first place.

How to tell flu, RSV, and Covid-19 apart

Currently, all three respiratory viruses are on the rise in the United States. RSV has been particularly prevalent among young children, with CDC data showing that there were almost 7,000 positive RSV tests last week.

Because all three viruses affect the respiratory system, they may manifest similar symptoms, such as a cough, runny nose, and fever, that make it difficult to tell them apart. However, there are a few subtle differences between the three viruses.

Influenza

Flu's incubation period is relatively short, with a range of one to four days and an average of two days. Some common symptoms of flu are a high fever, cough, sore throat, nausea, body aches, vomiting, and diarrhea. A high fever that reaches 103 or 104 degrees Fahrenheit is typically a distinctive feature of flu or influenza-like illnesses. The symptoms of flu are often more severe than those of other viruses.

For young children, there is a higher risk of complications from the flu, including:

• Pneumonia
• Dehydration
• Sinus/ear infections
• Inflammation of tissues in the

RSV

According to Cleveland Clinic, RSV can infect people of all ages, but young children and older adults are most vulnerable to severe illness. The incubation period for RSV ranges from two to eight days, with an average of five days.

Children's "airways are smaller, so inflammation and extra mucus make it harder for them to breathe," said Joe Childs, a physician at East Tennessee Children's Hospital. "Especially in the first few months of life, it can be very nasty."

Many symptoms of RSV, including a runny nose, coughing, sneezing, and fever, are similar to symptoms of other viruses, but one unique symptom is wheezing. This wheezing may sound like a whistle or a rattle when a person breathes.

If not treated, the wheezing may worsen into bronchiolitis or pneumonia. Patients with asthma or other respiratory conditions may be more susceptible to severe outcomes with RSV.

Covid-19

The incubation period for Covid-19 ranges from two to 14 days, with an average of three days before symptoms appear. In general, many of the symptoms of Covid-19 are similar to flu, RSV, and other respiratory viruses.

Although a loss of taste and smell is often considered to be a symptom unique to Covid-19, other viruses, including those that cause the common cold and flu, can affect someone's sense of taste and smell.

However, unlike other respiratory illnesses, Covid-19 can have a serious effect on the body outside of the lungs. "Flu can do this too, but the symptoms usually go away once the virus leaves your lungs," said Frank Esper, a pediatric infectious disease specialist at Cleveland Clinic. "COVID can cause long-term effects, such as brain fog."

Overall, even with some viruses causing different symptoms, health experts say that observing symptoms alone is typically not enough for people to determine what they are sick with. A test for each specific virus is often recommended, especially for individuals with underlying medical conditions who have an increased risk of severe illness.

"What I would emphasize, in my way of thinking about this, is not for people to try to guess exactly what the virus is, but rather to understand that there are many different respiratory viruses that are circulating" said Ian Michelow, head of pediatric infectious diseases and immunology at Connecticut Children's Medical Center.

How to avoid getting sick in the first place

Although it may be difficult to tell respiratory viruses apart, there are steps that people can take to avoid, or at least reduce the risk of, infection in the first place:

• Wearing a mask
• Keeping physical distance from others
• Washing your hands regularly or using hand sanitizers
• Sanitizing high-contact surfaces, such as tables, desks, and doorknobs if someone in your household is sick
• Getting vaccinated against flu and Covid-19

If you or your child does end up getting sick, health experts recommend staying home from work or school to avoid spreading the virus to other people.

"Whatever people can do to mitigate spread of any virus that would require hospital care I think we should do, because the hospitals are so strained," said Scott Roberts, associate medical director for infection prevention at Yale New Haven Hospital. "The last thing we need right now, on top of the 41 kids with RSV in the children's hospital, is more and more kids coming in with the flu that takes bed space." (Stannard, Hartford Courant, 10/28; Bink, Nexstar/The Hill, 10/30; Cleveland Clinic, 10/27)