Published Dec 7, 2023

Do I have Covid-19, the flu or RSV?

Dr. Sudip Bose
Medically reviewed by
Dr. Sudip Bose
Photograph from above of a Black family in bed, with a man and woman cuddling two small children.
Published Dec 7, 2023

Key Points:

  1. Different viruses cause Covid-19, influenza and RSV. But the illnesses share many symptoms, so it can be hard to detect which virus you have.
  2. You can have more than one virus at the same time—but it’s not common.
  3. At-home combination PCR tests for Covid-19, the flu and RSV do exist. But they can be expensive if not covered by health insurance.

When we huddle inside to escape the winter chill, respiratory viruses can spread and hit us hard. On top of getting your Covid-19 vaccine, flu vaccine and RSV vaccine, staying home when sick is the best way to help yourself heal while keeping others safe.

But how can you tell if you have Covid-19, the flu or respiratory syncytial virus (RSV)?

Here are some helpful distinctions to consider this virus season. Plus, how to get Covid-19 and flu treatment from Dr. B through a convenient online consultation.

What’s the difference between Covid, flu and RSV?

Respiratory illnesses like the common cold, Covid-19, the flu and RSV are caused by different viruses. They spread through the air via infected drops that enter our body through our nose, mouth and (sometimes) eyes. They can also live on surfaces and spread when we touch the infected surface and then touch our face.

Because they’re caused by different viruses, Covid-19 can’t turn into RSV. The flu virus can’t cause RSV. And RSV can’t morph into Covid-19 or the flu.

Here are some ways to figure out which virus you have:

The flu

  • The flu is caused by the influenza virus
  • Flu symptoms usually hit hard and fast. 
  • Symptoms include fevers, muscle aches, chills, sweats, fatigue, and headaches. 
  • You can test positive for the flu one day before symptoms start + up to seven days after feeling sick. 
  • You’re most contagious during the first three or four days of symptoms. But some people—including infants and those immunocompromised from other health conditions—can be contagious for more than a week.

RSV (respiratory syncytial virus)

  • A common virus, RSV often feels like a mild cold, with symptoms like a runny nose, coughing, sneezing, wheezing, fever and decreased appetite. 
  • Most people are contagious during the first week of infection and feel better in a week. 
  • RSV can be dangerous for infants and is the most common cause of bronchiolitis and pneumonia. In infants and those with compromised immune systems, RSV can continue to spread for up to a month.

Covid-19

  • Covid-19 is caused by SARS-CoV-2. 
  • Current mild-to-moderate symptoms include headaches, fatigue, muscle aches, fevers or chills, sore throat, congestion or a runny nose, nausea, vomiting and diarrhea. 
  • People with symptomatic infections reach peak viral load between days three and six. But you can be contagious for ten days after symptoms present.

Can you have Covid, flu and RSV at the same time?

You can have more than one virus at the same time. But research suggests this is rare.

When our immune system detects any virus it deems a threat, it revs up with a general protective response. After that, it homes in on the particular virus. So if we’re already armed to fight one virus, it can be difficult for a second infection to take hold.

Different people make varying immune responses, so there’s no way to know how long your immune system will stay on guard, and you can get another virus within a few weeks or months. That’s why we’ve seen Covid-19, the flu and RSV make individual waves—not peak together.

Can I get at-home tests for Covid-19, flu and RSV?

The easiest way to determine if you have Covid-19, the flu or RSV is to call your healthcare provider. But at-home tests are available for all three viruses. They vary in how easy they are to use, their cost and how fast you’ll get results.

Covid tests

At-home Covid-19 tests detect antigen proteins from SARS-CoV-2. They’re less reliable than PCR tests, which detect SARS-CoV-2 RNA and are done by a health professional. To make sure you’re negative for infection, the FDA recommends repeating at-home tests every few days.

Every household can sign up to get four free at-home Covid-19 tests through the federal government. Some insurance carriers will pay for or reimburse you for Covid-19 tests bought at your local pharmacy.

Combination tests for flu, RSV and Covid-19

Quest Diagnostics and LabCorp make at-home combination tests for Covid-19, the flu and RSV. You take a sample, send it in for lab testing, and get the results back in one or two days. You’ll have to get a prescription from your health provider to have your insurance cover the cost. Otherwise, they can cost over $150 each out of pocket.

In February 2023, the FDA authorized an at-home combination test for Covid-19 and influenza. Made by Lucira, you take a sample from your nose and insert it into a small device, which shows your results within 30 minutes. But these tests can be expensive—and hard to find.

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Sources:

Boucau, J., et al. (2022). Duration of shedding of culturable virus in SARS-CoV-2 Omicron (BA.1) infection. New England Journal of Medicine.

The Centers for Disease Control and Prevention. (2023). Covid-19.

The Centers for Disease Control and Prevention. (2022). How flu spreads.

The Centers for Disease Control and Prevention. (2023). Respiratory syncytial virus.

Manjarrez, A. (2022). What happens when you catch more than one virus? The Scientist.

The Mayo Clinic. (2023). Influenza.

The Mayo Clinic. (2021). Respiratory syncytial virus.

US Food and Drug Administration. (2022). At-home COVID-19 antigen tests—take steps to reduce your risk of false negative results.

US Food and Drug Administration. (2023). FDA authorizes first over-the-counter at-home test to detect both influenza and Covid-19 viruses.

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