How COVID-19 is different and worse than the flu

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Editor’s note: As what we know about COVID-19 evolves, so could the information contained in this story. Find our most recent COVID-19 blog posts here, and learn the latest in COVID-19 prevention at the Centers for Disease Control and Prevention.

There are reasons to compare flu and COVID-19. Both are infectious respiratory illnesses that can cause similar symptoms, including fever and body aches. Both are more likely to cause serious illness and death in people over age 65. But they’re also very different because the two illnesses are caused by different viruses.

How is COVID-19 worse than the flu?

What makes COVID-19 so much more dangerous than the flu is that there’s no vaccine and no natural immunity in the world, meaning everybody is susceptible. A flu vaccine is available and effective to prevent some of the most dangerous types of the virus or to reduce the flu’s severity.

Antiviral medications can address flu symptoms and sometimes shorten the duration of the illness.

Unlike the flu, there are no proven antiviral treatments for COVID-19. In addition, COVID-19 appears to be about 10 times as deadly as the flu. People who contract coronavirus face a far greater risk of death than those who get the flu, according to the World Health Organization. WHO also says that COVID-19 is 10 times deadlier than the H1N1 swine flu strain.

The death rate for flu—usually about 0.1%—is thought to be many times lower than for the coronavirus. The current best estimate for the coronavirus is 1%.

And, because nobody has natural immunity, the number of individuals who could be infected and may have a fatal case of COVID-19 is everybody in the world vs. a subset of individuals in the case of influenza.

How is COVID-19 different than the flu?

COVID-19 has both similarities and differences with the common flu. Both are viruses that actually are not live entities but packets of genetic material, and distinguishing between the two isn’t always easy. But there are some generalities that may be helpful.

  • It’s not uncommon for both to cause fever, as well as fatigue and tiredness. Body aches and headache tend to be more common with the flu than COVID-19.
  • One potential distinguishing factor is a runny nose. Nasal congestion and runny nose are common with the flu, but quite infrequent with COVID-19. Some sources suggest only a 5% presence in coronavirus cases.
  • In addition, COVID-19 may also cause a loss of smell or taste sensation. The flu doesn’t.
  • Although initially diarrhea as well as nausea and vomiting were thought not to be a common symptom in COVID-19, this belief has been shown to be incorrect.
  • COVID-19 spreads more easily than the flu. The incubation time from exposure to first symptoms for the flu, 1 to 4 days, is short compared with 1 to 14 days for COVID-19.
  • Symptoms last longer for COVID-19, from 7 to 21 days, compared to a week or two for the flu.
  • There doesn’t appear to be a COVID-19 season, while there is a flu season.

Randell Wexler is a primary care physician at The Ohio State Wexner Medical Center and a professor of family medicine at the Ohio State College of Medicine.