5 Reasons Why COVID-19 is More Dangerous Than the Flu

5 Reasons Why COVID-19 is More Dangerous Than the Flu

Both are highly contagious respiratory viruses but there are several key differences you need to understand.

Updated on October 27, 2020 at 9:00am EDT.

Comparisons between COVID-19 and the flu—or even the common cold—may be leading to some confusion about these highly contagious respiratory infections.

Younger adults, in particular, may have the misconception that COVID-19 is only serious for older people and those with chronic health issues. In fact, adults of all ages have become severely ill.

There are some other key differences between COVID-19 and influenza that you should understand, especially now that a new flu season is underway.  

COVID-19 appears to spread more easily
The common cold, the flu and COVID-19 can all spread from person to person through direct contact or droplet transmission.

Contact transmission includes direct exposure to someone who is sick. This includes shaking hands, hugging or kissing. It can also occur when people touch a contaminated surface and then touch their mouth, nose or eyes.

Those who are sick can also infect others when contaminated droplets from their coughs or sneezes land in a nearby person’s mouth or nose. Droplets can also travel about six feet before settling on a nearby surface where they can persist for hours or, for some viruses, even days.

In early October 2020, the Centers for Disease Control and Prevention (CDC) revised its guidance on how SARS-CoV-2, the coronavirus that causes COVID-19, spreads. The agency warns that under certain conditions, the coronavirus could spread through the air in contaminated aerosols—particles even smaller than respiratory droplets that may waft and accumulate.

The agency notes that this is more likely to occur indoors, particularly in areas with poor ventilation or where people are singing or exercising. 

The CDC also revised its definition of “close contact.” Before, close contact meant spending at least 15 continuous minutes within 6 feet of an infected person. It is now defined as being within 6 feet of those with COVID-19 for a total of 15 minutes or more over a 24-hour period, starting from 2 days before they were tested or developed symptoms until they were isolated. This means that shorter but repeated exposure that adds up to 15 minutes over the course of one day counts.

Bottom line: COVID-19 spreads very easily—possibly even more efficiently than the flu.

People with COVID-19 may be infectious longer
Most people with flu are contagious for about one day before they develop symptoms of the infection. Older kids and adults with the flu are most contagious after three to four days but may still pass the infection to others for about seven days.  

Scientists are still working to understand how long someone with COVID-19 remains infectious.

U.S. health officials warn that it’s possible for people to spread the coronavirus from about two days before symptoms appear until 10 days afterwards. Even after symptoms resolve, people may remain contagious for at least 10 days after testing positive for COVID-19. This is also true for those who never developed symptoms of the infection.

COVID-19 is more deadly
One of the most important differences between the flu and COVID-19: their mortality rates.

The flu is caused by different strains of influenza viruses. Symptoms of the infection come on more suddenly and tend to be more severe than a cold. While colds can lead to a sore throat, cough and runny nose, people with the flu may also develop a fever and experience chills, body aches and fatigue.

In most cases, people with the flu will recover within a couple of weeks. But some people—particularly older people, babies and very young children and those with underlying health issues—are more likely to develop complications such as pneumonia, inflammation of the heart, brain or muscle, sepsis or organ failure. In extreme cases, the flu can be fatal.

A severe flu season has a death rate of about 0.1 percent, according to a February 2020 editorial in the New England Journal of Medicine written by Anthony S. Fauci, MD, head of the National Institute of Allergy and Infectious Diseases (NIAID), H. Clifford Lane, MD, NIAID’s Deputy Director for Clinical Research and Special Projects and Robert R. Redfield, MD, Director of the CDC.

By comparison, the COVID-19 mortality rate appears to be higher. Just how much higher is still a matter of investigation. On March 3, the World Health Organization reported that about 3.4 percent of confirmed COVID-19 cases around the world are fatal. That would mean the novel coronavirus is more than 30 times more lethal than the flu, which claims tens of thousands of lives each year in the U.S. alone.

Keep in mind, researchers are still learning about SARS-CoV-2. Variables among countries, such as population demographics and the quality of health care, also influence estimates on mortality rate. For example, in South Korea—where aggressive testing took place—researchers calculated a COVID-19 fatality rate of closer to 0.6 percent.

More than 80 percent of those with COVID-19 will develop only a mild infection and recover. It’s widely believed that many more mild cases haven’t been detected and aren’t included in official counts. If the number of mild, unreported cases far exceeds the number of more serious, confirmed cases, the COVID-19 mortality rate could actually be less than 1 percent, the NEJM editorial pointed out.

CDC estimates updated on September 10 indicate that the COVID-19 infection fatality ratio (IFR) varies widely by age, or from 0.003 percent among children and teens to 5.4 percent among people in their 70s.

More people are vulnerable to COVID-19
Coronaviruses, like COVID-19, usually circulate among animals, particularly camels as well as cats or bats. When they mutate and infect people, most coronaviruses trigger mild to moderate illness. Only rarely do they lead to serious illnesses, as was the case with SARS-CoV, MERS-CoV and SARS-CoV-2.

Still, unlike the seasonal flu, COVID-19 is new. People around the world have built up immunity to some strains of influenza. This isn’t the case for COVID-19.

Older people and those with pre-existing medical conditions—such as asthma, diabetes and heart disease—are among those at higher risk for potentially deadly complications associated with COVID-19. These include pneumonia, acute cardiac injury, irregular heartbeat, shock and acute kidney injury.

Doctors know more about managing flu
There are currently no immunizations that protect against COVID-19 as there are for the seasonal flu. Moreover, for those who do become sick with the flu, there are four existing antiviral medications that can reduce the severity and duration of the infection.

The U.S. Food and Drug Administration has, so far, approved one antiviral drug called remdesivir for the treatment of adults and children age 12 and older who are hospitalized with COVID-19.

Meanwhile, scientists in the U.S. and around the world are urgently working to develop a COVID-19 vaccine. As of October 2020, 48 vaccines are being tested on humans, and at least 89 others are still being tested on animals.

Corticosteroids, such as dexamethasone or hydrocortisone, which are used to suppress the immune system and ease inflammation may be used to treat patients with severe COVID-19.

In June, researchers in the UK announced some preliminary findings of the RECOVERY (Randomized Evaluation of COVID-19 Therapy) trial, which was launched in March to evaluate several existing drugs as possible treatments for COVID-19. The team found that low-dose dexamethasone could reduce deaths by up to one-third in very severe cases of COVID-19.

The RECOVERY trial is also investigating the effectiveness of the following drugs as potential COVID-19 treatments:

  • Azithromycin (an antibiotic)
  • Tocilizumab, which is sold under the brand name Actemra (an injectable anti-inflammatory treatment)
  • Convalescent plasma with SARS-CoV-2 antibodies (collected from people who have recovered from COVID-19)
  • Regeneron’s investigational antiviral antibody cocktail, known as REGN-COV2

Monoclonal antibodies (laboratory-made versions of natural antibodies against SARS-CoV-2) is another experimental COVID-19 treatment still under investigation.

How to protect yourself
You don’t need to wait for a vaccine or more antiviral treatments to help protect yourself and others from COVID-19. There is a lot you can do to avoid exposure and reduce your risk of infection to both the flu and COVID-19, including:

  • Getting a seasonal flu shot
  • Wearing a face mask or cloth covering when out in public or around other people
  • Practicing social distancing, or staying at least 6 feet away from others
  • Washing your hands well and often with soap and water for at least 20 seconds each time
  • Not touching any part of your face, including your eyes, nose or mouth with unwashed hands
  • Avoiding people with suspected or confirmed infections

If you think you might be sick
Anyone who believes they may be infected with COVID-19 or might have been exposed to the coronavirus should take immediate steps to isolate themselves and avoid spreading their illness to others.

If you develop any warning signs of infection you should call your health care provider (HCP) for instructions. Before going to a doctor’s office or emergency room, be sure to call ahead and inform the medical staff that you may have been exposed to COVID-19. Your HCP will help you determine if you need to be tested.

Medically reviewed in October 2020.

Anthony S. Fauci, MD, H. Clifford Lane, MD, and Robert R. Redfield, MD “Covid-19 — Navigating the Uncharted.” New England Journal of Medicine. Feb 2020. “Remarks by President Trump, Vice President Pence, and Members of the Coronavirus Task Force in Press Conference.”
Mayo Clinic. “Common Cold.” “Rhinovirus Infections.”
Centers for Disease Control and Prevention. “Flu Symptoms & Complications.”
Centers for Disease Control and Prevention. “Key Facts About Influenza (Flu).”
Centers for Disease Control and Prevention. “Transcript for the CDC Telebriefing Update on COVID-19.”
World Health Organization. “Rolling updates on coronavirus disease (COVID-19).”
Moderna. “Moderna Ships mRNA Vaccine Against Novel Coronavirus (mRNA-1273) for Phase 1 Study.”
National Institute of Allergy and Infectious Diseases. “NIH Clinical Trial of Remdesivir to Treat COVID-19 Begins.”
The Aspen Institute. “7 Things to Know About the Novel Coronavirus, According to the Experts.”
U.S. Food and Drug Administration. "Coronavirus (COVID-19) Update: FDA Issues Emergency Use Authorization for Potential COVID-19 Treatment."
Centers for Disease Control and Prevention. "Similarities and Differences between Flu and COVID-19​."
RECOVERY Trial. “RECOVERY COVID-19 phase 3 trial to evaluate Regeneron’s REGN-COV2 investigational antibody cocktail in the UK.” Sept 14, 2020.
Centers for Disease Control and Prevention. “COVID-19 Pandemic Planning Scenarios.” Sept 10, 2020.

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