Why COVID-19 Is Not Like the Flu or the Common Cold

A number of folks have asked me why COVID-19 is not like the flu, “just another flu,” or like the common cold. I’m going to try to answer those questions here. Please read #12 if you read nothing else! If you are a doctor, epidemiologist, public health professional, etc., please let me know if I should tweak anything.

Why Covid-19 Is Not the Flu

  1. COVID-19 is not the flu or the common cold for the same basic reason measles isn’t the common cold: they’re caused by completely different viruses.
  2. The virus is a “novel” coronavirus. That means we’ve never seen it before. We are still learning about it, and (#3 below) our bodies aren’t ready to fight it off.
  3. Because it’s a new virus, no one has built up any immunity to it, so everyone can get sick. With common strains of the flu or the common cold, some percentage of the population is immune either because of previous exposure or, in the case of the flu, because of vaccines. So, those viruses can’t spread as quickly as a new virus.
  4. We have vaccines for many strains of the flu, and we have anti-flu drugs (for example, Tamiflu). Because COVID-19 is caused by a never-seen-before virus, there is no vaccine, and there are no drugs known to fight the virus directly. A vaccine is at least a year, possibly 18 months, away. In the meantime, the virus can keep infecting and killing new people. It’s true that flu vaccines aren’t 100% effective because different strains of flu go around every year. But flu vaccines work infinitely better than 0% of the time, which is where we are with COVID-19 right now.
  5. COVID-19 is much more contagious than the flu, so it spreads much faster. On average, a person who gets the flu will give it to roughly 1.3 other people. On average, a person who gets the virus that causes COVID-19 will give it to roughly 2.2 to 2.5 other people. A single person (“Patient 31”) in South Korea may have infected dozens people, leading to hundreds or maybe even thousands of new cases by going about life as usual—attending church and eating at a hotel buffet—before her diagnosis.
  6. A new virus that is causing an epidemic or pandemic doesn’t grow linearly; it grows exponentially until it runs out of opportunities to spread. That is, if you hear that there were X new cases of COVID-19 yesterday, you shouldn’t expect X new cases today; you should expect many more at this stage of things. The number will go up every day until the virus starts running out of opportunities to infect people, either because too many people are already sick or because we get really serious and cut down the transmission rate.
  7. You may have heard that coronaviruses cause the common cold. That’s only partially true; some coronaviruses that infect humans cause the common cold. Others cause extremely serious, very deadly diseases like SARS and MERS. The coronavirus that causes COVID-19 can kill people, not just cause a cold.
  8. COVID-19 is much deadlier than a common cold or common strains of the flu. Seasonal flu kills only about 0.1% of patients (1 in 1,000). So far, COVID-19 has killed 4% of people known to be infected (1 in 25). But this number doesn’t tell the whole story. Some of the people who are currently infected will get better, but some will die. It can take a long time—2 to 8 weeks—for patients to die from COVID-19, and 2 to 6 weeks for people to recover. Globally, for people whose outcome (recovery or death) is known, 7% have died (1 in 15). As we learn more about how many people have been infected and as more people are treated, experts think these numbers may go either down or up.
  9. This virus can sicken and kill people at almost any age, but it is especially significant for people who are older or have serious health issues. While the flu typically kills about 1% of people over 80 years old, COVID-19 kills about 15% of people that age. Put differently, there’s about a 1 in 7 chance that an 80-something-year-old person with COVID-19 will die, even with the best medical care. Many younger people have died, too; the reality that it hits older people hardest doesn’t mean it doesn’t kill younger people.
  10. COVID-19 causes much more serious illness than common flu strains, even in many people who survive. You may have heard that 80% of people experience a “mild” illness with COVID-19. That appears to be true, but that means that 20% of people experience serious illness, and some of those people die, even with great medical care. This includes people who are young and healthy.
  11. Because so many people get very sick, COVID-19 can overwhelm our entire health care system. Many of those 20% of people who experience serious illness need hospitalization, and many of those will need to be on a ventilator in intensive care. The United States has only about 60,000 ventilators, far too few to cope with the demand in the worst-case scenarios. The result is that doctors could be forced to decide who gets care and lives and who doesn’t get care and dies. In other words, some people will die not just because they’re sick but because the healthcare system is swamped and cannot care for everyone. This happened in China, it is happening now in Italy, and the United States is on a trajectory like Italy’s, if not worse.
  12. If we let COVID-19 keep spreading without major changes to daily life, it will overwhelm the entire healthcare system (see #11). This means that countless thousands or even millions of people will die because they are not be able to get treatment. And the longer we wait to act, the more likely this becomes, and the higher the numbers go. That is why everything is shut down: it’s literally a matter of life and death.

I hope this is helpful. Please feel free to share/repost it or to ask questions in the comments.

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If you’d like to know more or see where I got the information above, these links may be helpful:

Johns Hopkins Medicine: “Coronavirus Disease 2019 vs. the Flu” https://www.hopkinsmedicine.org/health/conditions-and-diseases/coronavirus/coronavirus-disease-2019-vs-the-flu

World Health Organization: “WHO Director-General’s opening remarks at the media briefing on COVID-19 – 3 March 2020” https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19—3-march-2020

Worldometers: “COVID-19 Coronavirus Outbreak” https://www.worldometers.info/coronavirus/

Centers for Disease Control and Prevention: “Transcript – CDC Media Telebriefing: Update on COVID-19” https://www.cdc.gov/media/releases/2020/t0309-covid-19-update.html

Live Science: “13 Coronavirus myths busted by science”  https://www.livescience.com/coronavirus-myths.html

Reuters: “The Korean clusters: How coronavirus cases exploded in South Korean churches and hospitals” https://graphics.reuters.com/CHINA-HEALTH-SOUTHKOREA-CLUSTERS/0100B5G33SB/index.html

Center for Infectious Disease Research and Policy (University of Minnesota): “Study of 72,000 COVID-19 patients finds 2.3% death rate” http://www.cidrap.umn.edu/news-perspective/2020/02/study-72000-covid-19-patients-finds-23-death-rate

USA Today: “Coronavirus is spreading in the US. Here’s everything to know, from symptoms to how to protect yourself” https://www.usatoday.com/in-depth/news/health/2020/03/05/coronavirus-us-cases-symptoms-travel-deaths-prepare/4904568002/

NPR: “As The Pandemic Spreads, Will There Be Enough Ventilators?” https://www.npr.org/sections/health-shots/2020/03/14/815675678/as-the-pandemic-spreads-will-there-be-enough-ventilators

Washington Post: “Spiking U.S. coronavirus cases could force rationing decisions similar to those made in Italy, China” https://www.washingtonpost.com/health/2020/03/15/coronavirus-rationing-us/

ProPublica: “This Coronavirus Is Unlike Anything in Our Lifetime, and We Have to Stop Comparing It to the Flu” https://www.propublica.org/article/this-coronavirus-is-unlike-anything-in-our-lifetime-and-we-have-to-stop-comparing-it-to-the-flu

Washington Post: “Why outbreaks like coronavirus spread exponentially, and how to ‘flatten the curve’” https://www.washingtonpost.com/graphics/2020/world/corona-simulator/

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Please note that all information above is as of March 17, 2020, based on the links above and current, publicly-reported counts of infections, deaths, and recoveries. Things are moving very quickly, so some of these numbers may become inaccurate over time. That’s part of why we need to take this so seriously: the situation changes so fast that we all need to keep educating ourselves.

Edited 2 hours after I posted it because the global death rate for known outcomes jumped from 7% to 9%. Things are happening fast.

Note: This was originally posted on Facebook, but Facebook decided 9 hours later that it was spam, without telling me why they made that decision. They gave me no options to improve it and restore it. So, I’m posting it here.






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