​How Do You Know if You Have COVID-19, Flu, or RSV?

Woman not feeling well in bed

Respiratory illnesses are on the rise this winter season. But it can be difficult to determine whether your illness is RSV, the flu, or COVID-19.

While taking a COVID-19 test is the only assured way to determine on your own if you have contracted that virus, being aware of their respective symptoms can help inform your treatment. In all cases, it is recommended that you rest, take time to recover at home, and wear a mask when around others to limit the spread of illness.

"We may not be able to eliminate these illnesses altogether, but we certainly can take measures to mitigate them as cases of COVID-19, flu, and RSV go up," says Dartmouth Hitchcock Medical Center’s Chief Quality Officer Michael Calderwood, MD, MPH, a specialist in infectious diseases. "And doing what we can to prevent and keep them from getting worse and spreading is even more important as hospitals fill up and business and schools are impacted by increases in the community."

The range of early symptoms

While differences can seem subtle, some exist, and these can serve as signposts when you first become ill.

"It can be hard to distinguish between illnesses caused by the different respiratory viruses, but generally speaking, the flu often comes on quickly, typically with fever, chills, body aches, fatigue, and a dry cough," says Calderwood.

In contrast to the flu, RSV usually comes on gradually. "People often report congestion, such as a runny or stuffy nose, at times accompanied by sneezing," he says. "Wheezing (a high-pitched whistling with breathing) is also seen more often with RSV than with the other respiratory viruses."

COVID-19 is different from flu or RSV in that it can appear in different forms. "While we see many of the same symptoms such as cough, fatigue, and headache, COVID-19 may also present with nausea or vomiting, diarrhea, or sudden loss of taste and/or smell. A sore throat also seems to be more common with COVID-19 than with flu or RSV," says Calderwood.

When in doubt about what respiratory illness you might have, always test for COVID-19. To purchase a test, you can go to your local pharmacy. The federal government still offers free rapid COVID-19 tests through the mail. You can order 4 free tests at COVIDTests.gov and they will be delivered by the U.S. Postal Service.

How to treat

When these illnesses are not severe, rest, fluids, and good care can go a long way toward recovery, but keeping a close eye on the severity of any illness is important. Remember, too, that if you are concerned about how an illness is presenting, consult your doctor.

For RSV

For RSV, it is particularly important to closely monitor adults and children with certain existing medical problems—such as heart disease, cystic fibrosis, and certain lung diseases. The elderly have weaker immune systems overall, so keep a close eye on them. Babies in their first respiratory virus season can be particularly at risk with RSV, points out Dartmouth Hitchcock Medical Center Section Chief of General Pediatrics, Susanne Tanski, MD, MPH. That’s because not only do people get the sickest when first exposed to the respiratory illness, but a baby’s tiny airways can lead to more severe disease, she says.

For flu

Flu, like all illnesses, also should be monitored. The CDC, in its flu treatment recommendations, suggests that antiviral drugs may be a treatment option for some, particularly those at higher risk. Consult your doctor to find out if they are right for you. Antiviral drugs work best when started early, such as 1 to 2 days after your flu symptoms begin. People at higher risk of flu complications include young children, adults 65 years of age and older, pregnant people, and people with certain medical conditions such as asthma, diabetes, and heart disease.

For COVID-19

The CDC offers guidelines on how to treat COVID-19 and says that most symptoms can be treated with over-the-counter medications, such as acetaminophen or ibuprofen. The FDA also has authorized or approved several antiviral medications used to treat mild to moderate COVID-19 in people who are more likely to get very ill. Those more at risk include adults aged 50 or older, people who are unvaccinated or not up-to-date on their vaccines, and people with certain medical conditions. A healthcare provider will help decide which treatment is right for you. If you are taking other medications, check with your provider or pharmacist to make sure the COVID-19 treatments can be safely taken at the same time.

Prevention

All people, but especially those in high-risk categories, can take precautions to stave off illness by wearing masks, avoiding crowded places, and washing their hands. If you are sick, stay home and keep away from other people.

Be sure to get your vaccines, too. The most recent COVID-19 vaccines from Pfizer-BioNTech, Moderna, and Novavax help lower chances of serious illness or hospitalization, including this season’s COVID-19 variant JN.1. If you already have had COVID-19 and are wondering if you need another vaccination, Calderwood provides these tips. The latest data on the protection that these new vaccines provide in the current respiratory virus season has just been published.

As far as the flu, most people need only 1 dose of influenza vaccine for the season, ideally prior to November. However, says the CDC, vaccination should continue throughout the season as long as influenza viruses are circulating.

To help prevent or minimize the effects of RSV, the CDC says adults 60 years of age and older have the option to receive a single dose of the RSV vaccine, based on discussions between the patient and their healthcare provider. It also recommends that pregnant women get a single dose of RSV vaccine between week 32 through week 36 of pregnancy. For those with babies under the age of 8 months, parents should ask their pediatrician about Nirsevimab, the new passive immunization that protects babies from severe RSV disease.

Concludes Calderwood: "Staying up to date with your vaccines, taking measures to protect and care for yourself and your loved ones, and being aware if you are at higher risk of severe illness, all can go a long way toward mitigating their severity and keeping these illnesses from spreading further this winter season."

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