Is it flu, covid or RSV? Table for distinguishing symptoms.

Three different viruses are sending children and adults to hospital emergency rooms across the United States this winter. The coronavirus is not coming back just because new immune-evasive variantsbut flu and respiratory syncytial virus they are also spreading earlier than usual and at record rates.

Most people managed to avoid the flu and other infections like RSV in the past few years when the coronavirus was new and much of the population took steps to slow the spread of Covid, which also slowed the spread of other viruses. Our immunity to these viruses may have weakened during that period, and many children born during the pandemic he never got any immunity. As a result, more people are vulnerable to common winter viruses now that much of the country has put aside masks and social distancing and is traveling more and congregating indoors.

To make matters worse, we could also be more susceptible to serious illness if we do get sick, said Dr. Priya Soni, a pediatric infectious disease specialist at Cedars-Sinai Guerin Children’s in Los Angeles.

“You can get really sick, maybe more than you normally would because your immune system really hasn’t been as compromised lately,” she said.

Here’s a guide to spotting the symptoms — and what to do to confirm and treat various infections.

There is overlap between cold, flu, Covid and RSV symptoms

Check your symptoms below, then sort by selecting a disease.

Flu, Covid and RSV have overlapping symptoms — and can also look quite similar to those of the common cold, which are caused by different viruses. You can develop a cough, fever, headache or runny or stuffy nose with any respiratory virus, said Dr. Michael Chang, an infectious disease specialist at Memorial Hermann Health System in Houston. But one way to distinguish between viral infections is to track how quickly your symptoms increase.

Flu symptoms appear quickly—often just a day after exposure to someone who was sick—and can be felt throughout the body. People with the flu often describe feeling like they’ve been hit by a truck, Dr. Chang said. With a cold, symptoms may take two or three days to appear and are much milder. Covid and RSV have even longer incubation periods. It can take an average of five days from exposure to the coronavirus to develop early symptoms of Covid-19, although newer variants can lead to active infection as early as three days after exposure. RSV lasts about four to six days. With Covid and RSV, symptoms also develop slowly: you may start feeling the sniffles, then the next day you have a cough or headache, and the next day you have a fever.

Adults with the flu are likely to have very high temperatures, up to 103 or 104 degrees, Dr. Chang said. But fever rarely follows a cold, especially in adults. And those with Covid-19 and RSV have a mild fever or none at all. “Especially with the newer variants and people who have been exposed through immunization or if they’ve already had an infection, we’re seeing more patients now with only mild symptoms and only a low-grade fever, around 99 or 100,” Dr. Chang said.

Other, less common symptoms can also help you distinguish the disease. For example, influenza and Covid-19 can cause diarrhea and vomiting; these gastrointestinal problems are more likely in young children. Covid-19 can also lead to a sudden and severe loss of taste or smell, which is very different from the temporary dimming of those senses when you have a stuffy nose from a cold or flu, Dr. Chang said.

People with RSV are less likely to experience the full-body fatigue and muscle aches that come with the flu or Covid-19. Instead, RSV is often accompanied by a very wet and forceful cough. “Of the three viruses, RSV will have the most mucus in the nose and throat and the most congestion,” Dr. Chang said.

Another characteristic symptom of RSV is wheezing, especially in young children. You can hear it as a high-pitched whistling or crackling sound when a sick child exhales. It may be accompanied by faster or more difficult breathing in general.

Your location matters.

Looking at community transmission rates in your area is another way to narrow down the possibilities of which virus you may have. While the official number of Covid cases may be understated due to increased at-home testing, you can still check the Centers for Disease Control and Prevention Covid-19 cardin addition to relying on local news and social media to find out if members of your community are sick.

Influenza and RSV tests must be performed in doctors’ offices or clinical laboratories and may be a more accurate representation of case rates nationwide. The CDC publishes this data in the weekly flu cards and RSV trends.

Some age groups are more vulnerable.

In general, adults over the age of 65 have the highest risk for all three viruses. This is because the body’s ability to fight viruses naturally declines with age. And older adults are more likely to have medical conditions that can put them at risk for serious symptoms and complications if they get sick.

Young children also tend to experience more severe flu and RSV symptoms because their immune systems don’t yet know how to properly fight pathogens, Dr. Soni said. Infants and young children also have smaller airways that block easily, making it more likely that their disease will progress from mild to severe and cause breathing difficulties.

Children are more likely to experience asymptomatic or mild Covid-19 infections compared to adults, Dr. Chang said, although “it is not well understood why this is so.”

Testing is the last word.

The only way to definitively diagnose or rule out one of these viruses is testing. Although you can easily test for Covid-19 at home, there are no rapid home tests for flu or RSV. There is a combined PCR test that he developed Labcorp which allows you to take a nasal swab for Covid-19, flu and RSV and mail the sample to a lab. But the results last a day or two.

Most clinics, emergency centers and hospitals also have combined tests for all three viruses, Dr. Chang said. But some doctors may forego diagnostic PCR if you have a mild infection. That’s because symptom management will remain the same for most people regardless of which respiratory virus they have, Dr. Soni said. (Those who fall into high-risk categories or are ill enough to be hospitalized may receive antiviral treatment for their infection, such as Paxlovid for Covid-19, Tamiflu for influenza, and ribavirin for RSV)

“The best most people can do is stay hydrated with lots and lots of fluids, keep a humidifier in the room and help younger children with nasal aspirators,” Dr. Soni said. Children and adults who are generally healthy and have no other health problems, she added, can try over-the-counter medications to relieve symptoms and will usually recover with little time.