There are probably plenty of people walking around with undiagnosed COVID-19 in the United States right now.

The Journal of the American Medical Association has a report of a woman who infected other people 19 days after becoming infected herself, and was asymptomatic (not sick) the whole time. BBC reporter Laura Bicker wrote that over 400 asymptomatic cases have been found in South Korea. However, the World Health Organization does not currently consider asymptomatic transmission to be a major vector, and Italy has stopped counting asymptomatic cases.

The COVID-19 Risk Profile

I’ve been doing a lot of reading about this, and people do not understand the risk profile of this illness.

Some people have caught the virus but not gotten sick. They may or may not be capable of transmitting the virus; the WHO and the Journal of the American Medical Association differ here.

Other people have caught the virus and only experienced a nasty flu. Right there, for me, that’s enough to set me on edge. I do not want a nasty flu.

But many people have caught the virus and needed to be hospitalized. The hospitalization rate is 15-20%. By contrast, the hospitalization rate for influenza in the United States is 0.053%. It’s so much lower that it’s typically reported not as a percentage (per 100) but as “52.7 per 100,000.” These numbers are estimates, and the science around this is changing very rapidly as new data becomes available, but this data indicates that COVID-19 makes you 300 to 500 times more likely to require hospitalization than the flu does.

If you’re in the “hospitalization” category, which again is roughly one out of every five or six cases, the specific reason for your hospitalization is severe pneumonia, sometimes so severe that it causes organ failure and keeps you in the hospital hooked up to a mechanical ventilator for a month (although the median hospital stay in Wuhan was only 10 days). The best estimates right now are that 38% of Italian patients needed hospitalization, and 7% needed intensive care. According to one unconfirmed tweet, multiple Italian hospitals have run out of space in their intensive care units, and this happened in Wuhan as well.


This makes me absolutely fanatical about this disease. I am planning to stay home a lot in the near future.

It’s not just about personal risk, but also mitigating the spread of the virus and being prepared. The slower the virus spreads, the more likely it is that virologists, hospital workers, and government can respond in time.

The United States does not have enough hospital beds for this illness, if it spreads quickly. The lowest credible estimate I’ve seen for the attack ratio (the best guess at infection percentage) is approximately 30%. So, if the hospitalization rate is 20%, with an attack ratio of 30%, in a population of 327 million people, then we could have 20 million people in need of hospital beds. (327 * 0.25 * 0.3 = 19.62.) But according to the CDC (PDF link, latest numbers 2015) and numerous other sources, there are slightly less than one million hospital beds in the United States.

If a bunch of people need hospital beds, but there aren’t any, those people are less likely to survive. So any step you take to limit or delay the spread of this illness is a step that could potentially save millions of lives. A lot of these numbers are just guesses right now, but if I can save 20M lives by staying home and playing video games, that’s what I’m going to do, at least until more definitive numbers exist.

(Also, I have also seen much larger estimates for the attack ratio, ranging from 40% to 70%, which would push the number of hospital beds needed to around 50 million, which is more than 50 times as many beds as we currently have. So it’s very important to do everything you can to slow the spread of the virus.)

Another point to remember: in the United States, if you’re in intensive care for a solid month, your next step is often bankruptcy.

Anyway, in addition to people who got the virus but haven’t gotten sick, and people who got the virus but only had a flu, and people who were hospitalized but still survived, there are also the people who died.

This disease mostly kills people who are elderly and/or people with other health problems. Important caveats:

What To Do

Here is an article by a Pulitzer-winning journalist who has covered more than 30 outbreaks and epidemics without getting sick. The article explains how to stay safe in a situation like this. The short version:

  • Keep your distance from other people, especially those who might be sick.
  • Wear gloves everywhere.
  • Change and wash them daily.
  • Never touch your face with your hands.
  • Wash towels frequently, and don’t share them, even among your family.
  • Be careful of doorknobs.
  • Open your windows when the weather allows.
  • Masks are mostly useless outdoors, but use them when treating a sick person in your/their home.

I strongly recommend that you read the long version as well.

The Carnegie Fellow, NY Times contributor, TED Talk presenter, and Harvard faculty member Zeynep Tufecki wrote this guide to surviving COVID-19 through good preparation, both the how and the why. The Australian virologist Dr. Ian Mackay wrote this article with a similar theme, and the Texan/Norwegian virologist Dr. Emma Hodcroft wrote this related Twitter thread.

The short version with prep is:

  • You want to have extra stuff ready in your house so you can avoid stressing the system you live in.
  • Have extra prescription medications on hand, in case the pharmacies get overwhelmed.
  • Have extra food in your house, in case the grocery stores or supply chains have issues.
  • Buy your extra stuff slowly. Panic buying strains the system.
  • Have treats, entertainment, and toiletries, and more (this is a good complete checklist).
  • Think about what you might need if your kids are staying home with you for a month: toys, games, and space for them to run around (not just for exercise, but also to tire themselves out).
  • Keep entertainment on hand in case the Internet goes down, and to prevent yourself from making bad decisions out of boredom (which has happened already in Chinese towns during lockdown situations).
  • Avoid doing anything which worsens the problem, not just out of self-preservation, but because the most helpful thing you can do as a member of society is to flatten the response curve. If 20 million people all need hospital beds at once in a country with only one million hospital beds, 19 million people are going to die. But if not everybody needs to be in the hospital at the same time — if all one million of those hospital beds are full every month for twenty months in a row — then a lot more people are going to be OK. So the most important thing to do is slow the spread of infection.

Again, though, I definitely recommend that you read each piece in full.

My current plan, although I hope to change it, is to follow all these instructions, self-isolate for the immediate future, play a bunch of video games, and read a whole ton of books. Please take this situation seriously; your life may depend on it, along with the lives of millions of other people.