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No, COVID-19 is not the flu

patient suffering from the coronavirus disease
REUTERS/Lucy Nicholson
Medical staff attending to a patient suffering from the coronavirus disease in the Intensive Care Unit, at Scripps Mercy Hospital in Chula Vista, California, on Tuesday.

Even as the death toll from COVID-19 climbs, there are people out there claiming the threat of the novel virus is being exaggerated and that it’s really no worse than a bad flu.

While it’s true that both are caused by viruses that are respiratory in nature and both have the potential to cause symptoms like coughs and fevers, it’s becoming increasingly clear they are not all that similar.

Their differences start with the packaging the viruses come in, and they continue through the way they attack people’s immune systems, even onto how deadly they are. Here’s a look at how they’re different and why.

They’re caused by different types of viruses

Influenza and coronavirus are two different families of viruses. While they both are made up of RNA (some diseases’ genetic material is DNA), the protein layers that surround the RNA, causing the immune response, are different in the two pathogens.

Influenza’s shell features hemagglutinin and neuraminidase proteins. Coronaviruses get their name from the glycoprotein spikes that surround them, giving them a crown-like appearance under magnification. Those different surface proteins interact differently with human cells.

Many types of common colds are coronaviruses, as are severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). COVID-19 is more closely related to those viruses than influenza.

The flu has been around for a long time, and we know a lot about it

Historians say the flu may date back millennia. Some of the first written descriptions of the virus are thought to date back to Hippocrates, around 410 BCE.

The influenza virus itself was identified in 1933, so people have had a long time to figure out how the flu works. We know when it’s likely to hit each year, and we know who’s more susceptible to severe complications.

“We know a lot about the flu. It’s got seasonality. We know what time of year it hits. We know that pregnant women, older people and young kids are at particularly high risk,” said Dr. David Ingbar, a professor of medicine, the director of the pulmonary, allergy, critical care and sleep division at the University of Minnesota’s Medical School and Executive Director of the Center for Lung and Science Health.

It’s not clear yet whether or to what degree COVID-19 will have a seasonal element, either. It could quiet down over the summer, or (perhaps more likely) it may not.

With COVID-19, patterns are emerging that suggest people who are older or have underlying conditions are at higher risk of severe complications, but much is still being learned — even every week, as the medical community learns more about the virus and even identifies new symptoms, like loss of taste and smell and rashes.

COVID-19 appears to be more transmissible

One of the numbers underpinning policy discussions about COVID-19 is something called an R0. Pronounced “R-naught,” this number refers to how many other people, on average, a person with a given virus will infect.

For seasonal influenza, the R0 is thought to be between 0.9 and 2.1, meaning the average infected person will infect one or two others. The Minnesota COVID-19 model currently predicts an R0 of 3.87, meaning the average infected person infects about 3.9 others. That means COVID-19 is more infectious than the flu.

Flu also has a shorter incubation period than COVID-19. It usually between one and four days for someone infected with the flu to show symptoms. With COVID-19, the  incubation period may be up to 14 days, making it more likely people will spread the virus before they show symptoms.

COVID-19 is often asymptomatic 

When Minnesota Department of Health researchers unveiled Version 3 of their COVID-19 model Wednesday, they increased the share of infections assumed to be asymptomatic from 25 percent to 41 percent. That’s a lot of people who could be walking around and infecting others without even knowing it.

If you get the flu,  on the other hand, you tend to get the flu — you show symptoms. There isn’t the same degree of asymptomatic carriers walking around with the flu without knowing it.

“Some individuals are reporting very mild illness due to COVID-19, and flu is usually pretty miserable for everyone,” said Melissa McMahon, a senior MDH epidemiologist working in vaccine-preventable disease surveillance, in an email.

For people who do have symptoms of COVID-19, there’s a range of them, from a headache to being wiped out to loss of taste, a skin rash and having a cough. Some, but not all, people seem to get fevers.

“I think of influenza as being more consistent in general,” Ingbar said.

COVID-19 is more deadly

It’s been tough for researchers to get a handle on the death rate of COVID-19, partly because so many people seem to be getting it without showing symptoms.

Early estimates in China put the death rate at around 3 percent. Recent research put the mortality rate in the U.S. around 1.3 percent, or a little over one in 100 infections.

That might not seem terribly high, but it’s much higher than a seasonal flu, which typically sees death rates around 0.10 percent, or one in 1,000 infections.

That suggests COVID-19 is about 10 times more fatal than a seasonal flu.

Some strains of flu are more deadly than others. The influenza virus is able to mutate quickly, and new strains have varying success at evading the human immune response.

“One part is immunity in how much your body recognizes it and defends against it. The other part is the mutation sometimes gives the virus extra potency, an ability to replicate more effectively or kill cells more easily,’ Ingbar said.

In terms of specific strains, flu tends to be deadlier in years where the A H3 strain is dominant, versus the A H1 strain. The A H3 strain is particularly severe for people over 65, McMahon said.

In Minnesota, there have been 683 confirmed deaths due to COVID-19 as of Friday morning. That’s four times higher than the number of people — 153 — believed to have died of flu so far this flu season. It’s one-third higher than the number of people who died of flu in 2017-18, a particularly deadly year when A H3 was prevalent, but Minnesota is believed to have yet seen the peak of COVID-19 cases and deaths.

Deaths from flu and COVID-19 in Minnesota by year
Note: Figures for 2019-20 cover flu season through May 9. Figures for COVID-19 in Minnesota include lab-confirmed deaths through May 15.
Source: Minnesota Department of Health

While COVID-19 is more deadly than influenza, people shouldn’t downplay the dangers of the flu, Ingbar said.

Ingbar said he sometimes has to work hard to convince patients to get a flu shot, particularly if they aren’t in any high-risk groups. Sometimes they cite imperfect rates of effectiveness, but even so, people who get flu shots significantly cut their chances of getting sick and feeling miserable for two weeks.

And some years more than others, the flu really can present risks to people’s lives.

“People forget that the flu itself can be a pretty serious illness,” Ingbar said.

Comments (25)

  1. Submitted by Sam Keats on 05/16/2020 - 06:40 am.

    There seems to be another difference, according to those who have been very ill yet recovered. So far, most of them don’t seem to fully recover. The fevers come back back, the exhaustion, the inability to catch a breath. The brain fog stays. Runners keep winding up back on the coach after any attempt to resume physical activity. And those who’ve had a stroke from the strange blood clotting aspect. . .

  2. Submitted by Cotty Lowry on 05/16/2020 - 06:40 am.

    Well done Greta! Of the dozens of articles I’ve read, this is the best comparison between the two diseases. My concern is mutation…will Covid mutate just like the flu does every year, obviating all work done to develop a vaccine?

  3. Submitted by Sandra Woessner on 05/16/2020 - 07:55 am.

    This is from the study paper you took to determine mortality rates:

    Our method does not account for a fraction of
    cases with the COVID-19 infection that recovers
    without any major symptoms. These asymptomatic patients do not contribute to any of the reported statistics on COVD-19 deaths and cases.

    How can your mortality statistic be right when it accounts for no asymptomatic carriers which you had just talked about in the previous paragraph? Fact is we just don’t know the mortality rate yet. No one knows if this will have a similar death rate to the flu or not.

  4. Submitted by James Roy on 05/16/2020 - 08:37 am.

    Gee, the flu is still “pretty serious”?? 650,000 die a year from that little ol’ flu!

    • Submitted by Mark Kulda on 05/16/2020 - 08:24 pm.

      That’s at the very high end of the WHO’s estimate which is that 290,000 to 650,000 die each year of the flu.

  5. Submitted by BK Anderson on 05/16/2020 - 09:23 am.

    This is really well done, thanks.

    But where, oh where, are our “conservative” friends, the online epidemiologists who assured us (in particular) that Covid-19 was going to end up having no greater mortality than the common flu?

    Early estimates of mortality per infection out of NYC data pegged the mortality rate at about .9, or about 9 times more deadly than the flu. When I referenced that number a couple of weeks ago, the rightwing Minnpost epidemiologists mocked it as absurd and preposterous. Now more and more data is coming in, is being widely reported, and it appears that early estimate was even slightly conservative!

    Does any “conservative” EVER admit they were wrong? From Trump on down, arrogance and denial.

    • Submitted by Tom Anderson on 05/16/2020 - 09:59 pm.

      Doctor F. said that COVID 19 wasn’t going to be that big a problem for the U.S. back in the beginning too. When all is said and done, the statistics will be counted and compared. Until then, everyone risks being wrong, in print.

      • Submitted by Alan Nilsson on 05/17/2020 - 10:57 am.

        From Politifact.com:
        ” Fauci did say twice in late January, when there was one reported covid-19 case in the U.S., that Americans shouldn’t worry about the virus. But Bannon (breitbart) omits an important detail: Both times, Fauci added that the situation could change.”

        The situation did change. When it did change, the administration showed that they did not rely on scientific advice.

        • Submitted by Tom Anderson on 05/17/2020 - 09:37 pm.

          The good doctor plays it well. Couldn’t any situation change? Well played doctor, well played.

          • Submitted by Pat Terry on 05/18/2020 - 11:03 am.

            That’s how science works. New evidence means new conclusions.

            If Fauci did anything wrong, it was failing to grasp just how incompetent the president is. He should have considered that Trump was an utter failure as a businessman, and would be a similar failure handling a real crisis.

    • Submitted by Orville H. Larson on 05/18/2020 - 07:36 pm.

      Fauci’s an ethically-challenged hack. Check out Gary Barnett’s article about him at LewRockwell.com.

      The Blessed One ain’t so . . well, blessed!

  6. Submitted by Mary Ollerich on 05/16/2020 - 10:40 am.

    Would you do an article on Dr. Judy Mikovits please. Thank you, Mary Ollerich

    • Submitted by kurt nelson on 05/16/2020 - 04:28 pm.

      Just go over to:
      Debunkednutjobs.com

      You’ll find all the info you need on that “scholar”.

    • Submitted by Brian Simon on 05/17/2020 - 01:06 pm.

      Interesting. Here’s what wikipedia has:
      “Judy Anne Mikovits (c. 1958) is a former American research scientist[2][3][10][11][12] who is known for her discredited medical claims such as murine endogenous retroviruses being linked to chronic fatigue syndrome. She has been described as an anti-vaccination activist[12][13] and a promoter of conspiracy theories, and has been accused of scientific misconduct.[6][7][8][9] She has made several false claims about vaccines, COVID-19, and chronic fatigue syndrome (CFS).”

      I’m not sure it’s worth digging much further.

    • Submitted by Pat Terry on 05/18/2020 - 11:09 am.

      There are plenty of articles explaining that Mikovits is a discredited lying nutjob. We don’t need to give people like that any more airtime.

  7. Submitted by Barbara Mcgraw on 05/16/2020 - 12:33 pm.

    Thank you! I still hear people contend this isn’t any worse than the flu – now I have some ammunition!

  8. Submitted by Randy Purchase on 05/16/2020 - 08:18 pm.

    Good job Greta; I wish you had gone in to the effects it has on the blood vessels and the blood clots and Covid toes, and how it can get in to major organs. Mother nature can be a serial killer, and one of her favorite tools is pandemic disease to thin the herd. I’m glad she has not turn us in to Zombies’ yet. Keep your mask on Greta.

  9. Submitted by Ron Gotzman on 05/17/2020 - 10:28 pm.

    I believe that over 82% of covid-19 deaths in MN are residence of LTC facilities?

    Is that the same with the flu?

    • Submitted by Pat Terry on 05/18/2020 - 01:52 pm.

      That’s a non-sequitir. The places where the worst of the outbreaks has been in this state doesn’t mean anything as far as distinguishing between Covid19 and the flu.

  10. Submitted by cory johnson on 05/20/2020 - 12:48 pm.

    They certainly aren’t the same. In fact, based on current data, the flu is at least 2.5 more deadly for children than covid. I guess we’ll have to close schools every year from November through March. Makes sense

    • Submitted by kelly barnhill on 05/22/2020 - 10:26 am.

      I can’t believe we have to explain this, but here we go:

      You’re right. The likelihood that a child in school will become seriously ill is quite small (though if you talk to one of the parents of children suffering from that strange, multi-system inflammatory response currently putting kids in the ICU, you might start seeing that risk differently). The reason why we closed the schools is not to protect children, but to protect grownups. The kindly seventy-two year old, for example, who drives a full busload of kids two and from school every day. Or the sixty-year old Middle School science teacher who has a husband with a heart condition. Or the thirty-year-old teacher with Lupus. Or the thousands of children who have an elderly grandparent who lives with them. Schools are incredibly germy places where close contact is pretty unavoidable.

      The flu is deadly, obviously, and needs to be taken seriously. But Covid-19 is far more communicable, and overwhelms a community extremely quickly. Families, neighbors, co-workers, friends. One transmission puts many people at risk. So it’s never just about one place, or one type of business, or one type of interaction. We need to think about the vulnerable AND the vectors that intersect with the vulnerable. And we need to protect, not ourselves, but each other.

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