Cases of both contagious viruses are on the rise right now.

Advertisement

It's easy to assume that if you or your child suddenly develops a cough and fever, COVID-19 is to blame. But rising cases of respiratory syncytial virus (RSV) over the spring and summer—particularly in kids—have made it hard to know for sure.

The Centers for Disease Control and Prevention (CDC) issued a health advisory in June, warning doctors about an increase in RSV cases across the southern US. "Due to this increased activity, CDC encourages broader testing for RSV among patients presenting with acute respiratory illness who test negative for SARS-CoV-2, the virus that causes COVID-19," the advisory said. It also noted that RSV can cause "severe disease" in young children and the elderly.

RSV-vs-COVID-GettyImages-1205739966
Credit: Getty Images

RSV infections in the US have surged throughout 2021, according to CDC data. The percentage of antigen and PCR laboratory tests coming back positive reached 42% the week of July 24, a time of the year when RSV is usually all but nonexistent. Data through August suggest the positivity rate remains high. At the same time, new COVID-19 cases have risen sharply. The seven-day average of new cases detected in the US topped 150,000 as of September 1, about 124% higher than a year ago, per the CDC.

So how can you tell RSV from COVID-19? Here's what you need to know.

What is RSV?

RSV is a common respiratory virus that usually causes mild, cold-like symptoms in most people, according to the CDC. It spreads a few different ways:

  • When an infected person coughs or sneezes
  • When virus droplets from a cough or sneeze get in your eyes, nose, or mouth
  • When you touch a surface that has the virus on it, like a countertop, and then touch your face before washing your hands
  • When you have direct contact with RSV, for example, by kissing the face of someone who has the virus

While RSV cases are usually mild, they can be serious. The virus is the most common cause of complications like bronchiolitis (an inflammation of the small airways in the lung) and pneumonia (an infection of the lungs), especially in children under the age of one, the CDC says.

Every year, RSV causes about 58,000 hospitalizations and up to 500 deaths in children under five. It also causes 177,000 hospitalizations and 14,000 deaths in adults aged 65 years or older, the CDC says.

What are the symptoms of RSV?

According to the CDC, symptoms can include:

  • Runny nose
  • Decrease in appetite
  • Coughing
  • Sneezing
  • Fever
  • Wheezing

What are the symptoms of COVID-19?

You're probably a COVID-19 armchair expert at this point, but it never hurts to recap, just for comparison's sake. COVID-19 is an infectious disease caused by the novel coronavirus, SARS-CoV-2, according to the Food and Drug Administration (FDA). COVID-19 is mostly a respiratory infection but it can impact other organs.

COVID-19 can cause serious complications, like pneumonia, and also a new range of illnesses known as post-COVID conditions. Post-COVID conditions, aka long COVID, can include things like difficulty breathing, fatigue, headache, diarrhea, and persistent loss of taste and smell.

The CDC says that symptoms of COVID-19 can include:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea

Can you get COVID-19 and RSV at the same time?

Unfortunately, yes. "Double infections can occur," infectious disease expert Amesh A. Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security, tells Health. Daniel Ganjian, MD, a pediatrician at Providence Saint John's Health Center in Santa Monica, California, agrees. "It's not so common, but it's definitely not impossible," he tells Health.

There isn't a lot of data to show how often double infections occur, but some research backs up the possibility. One study published in January 2021 of 78 patients in China found that 11 of them had a so-called co-infection. Of those 11, four had RSV in addition to COVID-19.

A retrospective study published in 2020 analyzed data from 862 patients at two medical centers in Chicago who tested positive for COVID-19 from March 9, 2020, through April 30, 2020. Of those, two tested positive for COVID-19 and RSV or the flu.

How does someone end up with RSV and COVID-19? You have to be unlucky enough to be exposed to both around the same time. "It just depends upon exposure," Dr. Adalja says.

Overall, though, this is not a common thing. "It would be unusual to be infected with RSV and COVID-19 simultaneously," infectious disease expert Richard Watkins, MD, professor of internal medicine at Northeast Ohio Medical University, tells Health. However, he adds, people who are immunocompromised or not vaccinated against COVID-19 are at an increased risk.

RSV vs. COVID-19: how to tell the difference

It's tricky. If you or your child develops symptoms, it's more than understandable to want to know what, exactly, is behind them. Unfortunately, even your doctor is unlikely to know just by doing an exam. "The acute illnesses for both are very similar clinically," Dr. Watkins says.

But there are a few clues that may crop up. "COVID-19 can sometimes cause vomiting, diarrhea, and a rash, which you don't see with RSV," Dr. Ganjian says.

Dr. Adalja agrees that it can be tough to parse these out, though. "There's no way to really distinguish the two conditions without a test," he says. So if you or a family member develops suspicious symptoms, call your doctor. It's likely they'll want to test you for both infections.

To get our top stories delivered to your inbox, sign up for the Healthy Living newsletter