Overlapping respiratory infections means your doctor could mistakenly clear you of COVID-19

One of the trickiest parts about the COVID-19 crisis is diagnosis. Right now, there are a lot of barriers to getting a prompt and accurate diagnosis — the shortage of tests, the fact that symptoms (and severity) vary from person to person, the overwhelm the medical community is facing right now.

All these factors are causing the virus to spread rapidly. But there may be another diagnosis-related factor contributing to the rapid spread of the virus — misdiagnosis.

There’s reason to believe that people may be getting diagnosed with other respiratory viruses (like colds and flu) when they have COVID-19. Why?

Because in many cases, people don’t have one or the other… they have both.

About 20% of COVID-19 patients also have another respiratory infection

New research from Stanford University shows that one in five people with COVID-19 also has another respiratory virus. This is a potentially big problem. Here’s why…

Since there’s a shortage of COVID-19 tests nationwide, the diagnosis process in hospitals and doctor’s offices is often a process of elimination. People are tested for more common respiratory viruses first. If they test positive, doctors assume that a more common respiratory virus is behind their symptoms and they don’t get further testing.

These people go home thinking they’re sick… but not COVID-19 sick. That means they may not be as concerned about isolation as they would be if they had COVID-19.

In this particular study, researchers looked at data from 562 people who were tested for COVID-19, 49 of whom tested positive. Most of these people (517) were also tested for other respiratory infections, like influenza A and B, respiratory syncytial virus, rhinovirus, adenovirus and several types of pneumonia. 127 of them tested positive for those.

But here’s where things get a bit concerning… researchers found that 22 percent of the confirmed COVID-19 cases also tested positive for another respiratory virus. They also found that 8.5 percent of the confirmed cases of other respiratory viruses tested positive for COVID-19.

Related: Why a lung condition makes you an easy target for COVID-19

So, there’s a significant overlap. According to researchers, that means that one in five people with the virus most likely has another respiratory virus as well. Researchers also reported that one in 10 people who go to the emergency room with symptoms of respiratory illness at an emergency department and get diagnosed with a common respiratory virus are co-infected with the COVID-19 virus.

“Currently, if a patient tests positive for a different respiratory virus, we believe that they don’t have COVID-19,” said Nigam Shah, MBBS, Ph.D., associate professor of medicine and of biomedical data science at Stanford medical school. “However, given the co-infection rates we’ve observed in this sample, that is an incorrect assumption.”

Take the same precautions for any respiratory infection

The good news is testing availability for COVID-19 is gradually improving. Drive-thru testing sites are popping up nationwide. But we’re still a long way from having accessible testing for everybody. And there’s even evidence that conventional diagnostic tests give false-negative results about 30 percent of the time.

Unfortunately, that means anyone who has a respiratory infection — whether it’s COVID-19 or not — should take the same precautions as those definitively diagnosed with the disease. It’s going to be a challenging few months (or longer) for everybody. But the threat will get better eventually. And we’ll all be that much more grateful to visit with our family, go to the bookstore, go see a movie and do all the things that we may have taken for granted until this crisis hit.


  1. COVID-19 patients often infected with other respiratory viruses, preliminary study reports — MedicalXpress
  2. Even if you test negative for COVID-19, assume you have it, experts say — Live Science
Jenny Smiechowski

By Jenny Smiechowski

Jenny Smiechowski is a Chicago-based freelance writer who specializes in health, nutrition and the environment. Her work has appeared in online and print publications like Chicagoland Gardening magazine, Organic Lifestyle Magazine, BetterLife Magazine, TheFix.com, Hybridcars.com and Seedstock.com.