Is it COVID, the flu, or RSV? A few hallmarks can help differentiate illnesses

COVID-19, flu, and RSV share many common symptoms, making it difficult to distinguish between them. Knowing what virus you have, however, can help determine the treatment you should receive and how long you should isolate yourself for.

Certain hallmarks — either symptoms or how the illness progresses — can help differentiate each virus.

Here are five factors to consider.

Symptoms such as a runny nose, cough, congestion, and sore throat are unique to specific viruses. However, any of the three viruses can cause them. Taste and smell loss are more commonly associated with COVID-19 than with the flu or RSV. Wheezing is often a sign of a serious RSV infection, often found in children and the elderly.

The only way to know for certain, though, is to get tested.

What is the onset of symptoms? Are they gradual or sudden?

In comparison to COVID or RSV symptoms, flu symptoms usually develop more suddenly.

Infectious diseases specialist Dr. Scott Roberts said that the flu typically begins with an abrupt fever, which happens pretty quickly. This is in contrast to RSV and COVID-19, which develop slowly over time.

How long has it been since exposure?

There is a difference between the incubation periods of the illnesses, the time between exposure and onset of symptoms. RSV symptoms usually appear around 4 to 6 days after exposure, while COVID’s typical incubation period is 3 to 4 days for the Omicron variant. Flu symptoms usually become apparent two days after exposure to the virus.

After attending a party and developing symptoms the next day, it’s probably the flu since it has a 24-hour incubation period.

Age makes a big difference in a disease’s symptoms and severity

Your age and immune status can also affect your symptoms. Due to the return to school and socialization, many kids are encountering respiratory viruses for the first time this year. As a result, their bodies may have a more difficult time clearing the infection.

According to Esper, almost a fourth of children have gastrointestinal symptoms — like diarrhea, stomach pain or vomiting — from viral infections. That’s less common in adults with seasonal flu or RSV.

People with weakened immune systems, meanwhile, are more likely to develop severe symptoms or pneumonia from any of the three viruses.

Symptoms to monitor as flu, COVID, RSV cases rise across the country 

Influenza cases may have peaked. There have been 25 percent positive influenza tests since at least two weeks ago. Hospitalizations for the flu are still at their highest level since more than a decade ago. 

Available treatments and vaccines

As with the flu and COVID-19, there is no universally prescribed treatment for RSV. At Palm Beach Research Center, we offer clinical studies for influenza, RSV and COVID-19. Visit our current studies page to see available treatment options.