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Coronavirus: what you need to know

How worried should you be about COVID-19 (also known as the "novel coronavirus disease" or "2019-nCov"), and should you start preparing for a potential pandemic?

I do not want to be alarmist. At the time of this writing – Tuesday, February 25 – the Centers For Disease Control and Prevention (CDC) does not recommend taking specific steps towards preparing for widespread coronavirus outbreaks in the United States. (Click here for a list of the CDC's current recommendations.)

Here's the CDC's most recent statement on the matter:

  • "More cases are likely to be identified in the coming days, including more cases in the United States. It’s also likely that person-to-person spread will continue to occur, including in the United States. Widespread transmission of COVID-19 in the United States would translate into large numbers of people needing medical care at the same time. Schools, childcare centers, workplaces, and other places for mass gatherings may experience more absenteeism. Public health and healthcare systems may become overloaded, with elevated rates of hospitalizations and deaths. Other critical infrastructure, such as law enforcement, emergency medical services, and transportation industry may also be affected. Health care providers and hospitals may be overwhelmed."

If you have not yet done anything to prepare for the possibility that COVID-19 could become widespread in your area, I think it is time to at least consider beginning preparations.

To help you decide whether or not you believe the risk is now high enough to actually begin to prepare, I've compiled some information about where things stand right now with the virus.

Keep in mind that the future of the virus is highly uncertain. It could blow over in a matter of months, but there is still unfortunately some chance that it ends up becoming an uncontrollable pandemic of global proportion. In the worst case, if we get extremely unlucky, it could potentially rival the largest pandemics in history.

In my opinion, if you're living in the U.S., the situation to be worried about is not so much the average or expected course for the disease that most people are anticipating right now, but rather, the more dangerous scenarios that have a 10% or lower likelihood of occurring. That's where things get really scary here. Things are already scary for many people in China.

I expect that this is the sort of event where we humans tend to overestimate how bad the average situation will be – because of the frequently sensationalist nature of journalism, and our tendency to fixate on new dangers – while at the same time substantially underestimating the tail risk (that is, not really grasping just how bad things could get if we turn out to be really unlucky).

Please note as you read this that I am not an expert on viruses. And if any of the information below is inaccurate, we would like to know. Please reach out and inform us if any of the below is incorrect.

Some facts as of Feb 24th, 2020 that may help you decide whether or not it's time for you to start preparing right now:

  1. Cases of COVID-19 have been confirmed in 35 countries.

  2. According to the CDC and the San Francisco Chronicle, at least two people have contracted COVID-19 while in the U.S.. Unfortunately, there is no way to know how many people in the U.S. are actually infected. The CDC has tested only 426 people here. According to a former FDA commissioner, screening is currently being rationed. Keep in mind that if or when a person dies of the virus, that would imply that many other people are already infected, since most cases will not lead to death – in fact, many cases may never be detected.

  3. The virus is highly infectious. The "basic reproduction number" (a.k.a. "R0") of an infection is "the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection." In other words, it's the average number of new people that each infected person will go onto infect in a population where most people have not yet gotten the virus. For COVID-19, one paper estimates R0 at about 2.3, but this number is far from certain. Another paper puts R0 much higher, in the 4.7 to 6.6 range. Regardless of which is more accurate, left to its own devices, the virus would initially infect people at an exponential rate if no interventions were undertaken. Humans tend to struggle with fully grasping the speed of exponential growth, and how it can go from no big deal to a huge problem before you know it. See, for instance, the famous "wheat on the chessboard" parable, where a king underestimates the power of exponential growth.

  4. Not everyone who gets infected with COVID-19 gets very sick. My understanding is that it's still quite uncertain how bad the virus is on average, partly because it has a long incubation period during which you can have no symptoms but still infect others. Most estimates I've seen say you can have the virus for 1 to 14 days before showing symptoms, but some say it could be even longer. Some small percentage of people who get the virus seem to never end up experiencing any symptoms at all, though there is some evidence they might still be contagious.

  5. People who are elderly are at a much greater risk of dying from the virus than people who are young. Currently, people who are younger than 40 seem to have a low death rate of 0.2%, whereas people 60-69 have a death rate of 3.6%, people 70-79 a death rate of 8%, and people 80-or-older a death rate of 15%. However, these numbers are quite uncertain at this stage due to limited information. Additionally, they depend on how high quality the local medical care is in a given region, and the extent to which that medical system is over capacity due to too many sick people. It's also worth nothing that even if you don't die from COVID-19, you may temporarily get very sick from it.

  6. Current information seems to suggest that about 14% of confirmed cases have been "severe, involving serious pneumonia and shortness of breath," whereas "5% of patients confirmed to have the disease developed respiratory failure," and "roughly 2.3% of confirmed cases did result in death." But keep in mind that these statistics are for people with confirmed cases. Since we don't know how many people have the virus, and since some people who have it are asymptomatic for up to two weeks (or may get sick without realizing that they have COVID-19), it's very uncertain how dangerous it really is.

  7. COVID-19 is much less deadly per person infected than SARS, since SARS had a mortality rate of around 10%. Yet because COVID-19 is spreading so much faster than SARS, it has killed far more people per month than SARS did. However COVID-19 appears to be more deadly than the flu, another common point of comparison – it has killed approximately 2.3% of patients in mainland China, while the flu kills about 0.1% of mainland Chinese patients.

  8. According to the Metaculus forecasting tournaments about the virus, as of today (February 25th, 2020) there is a 50% chance that the virus will have infected at least 6.3 million people worldwide by the end of 2020, a 25% chance it will have infected at least 60 million people, and a 9% chance it will have infected at least 1 billion people. Remember that most people who are infected will not die from it, and of course we don't know that the participants in the forecasting tournament are accurate, but still, that 9% estimated chance is extremely concerning.

  9. According to a related Metaculus forecasting tournament about deaths rather than infections, by the end of 2020, there is a 50% chance that the virus will have killed at least 52,000 people, a 25% chance it will have killed at least 772,000 people and a 3% chance it will have killed at least 100 million people. Since, in a typical year, only about 50 million people in the world die, 100 million dying from the virus would be an extremely large increase.

  10. Allegedly, more than 780 million people in China are now living under travel restrictions. And according to the Atlantic, "Starting in January, China began cordoning off progressively larger areas, radiating outward from Wuhan City and eventually encapsulating some 100 million people. People were barred from leaving home and lectured by drones if they were caught outside."

  11. I've been following the stock markets (Chinese and U.S.) to see what they think of the virus, and before today had been happy to see that the Chinese market had been recovering since the end of January. Over the past few days, however, the China 25 stock market Large-Cap index fell about 3.5%, with the S&P 500 (U.S. stock market index) falling about 3.3%. As far as I know, they might jump back up tomorrow, and these dips may not even be caused by COVID-19 – nobody can say for sure since so many things happen in the world on a given day. But this is the first sign I've seen since the end of January that the markets may be beginning to take this seriously., which is a China-based worldwide "leading provider of online travel and related services," fell 5.4% in the last few days.

  12. On the brighter side, according to this COVID-19 case tracker, which also shows where in the world each of the cases has occurred, the number of new infections per day has not been increasing exponentially as many people feared it would. But some claim that these numbers are artificial, because we may have hit the peak capacity in how many people can be tested each day, meaning that the number of true cases could be growing exponentially while the number of cases detected is not. Further, it's possible that governments are diagnosing new cases at a higher rate than they're disclosing those new cases. So it's an open question whether the growth rate of the virus is slowing overall, or whether that chart is just an artifact of our limited capacity to detect the virus. What we do know, however, is that the number of reported cases is limited by:

  • How many of the infected people have been correctly diagnosed. Remember that many don't display symptoms at first, some never do, and some who do develop symptoms may assume that they have a more common illness.

  • The daily capacity limit of testing facilities.

  • The number of cases the countries involved are willing to report. Some governments may have an incentive to downplay incidents.

  1. While some experts are clearly very concerned, there are others who say the danger is overblown (see for instance this February 14th article, or this one from February 20th). Both articles claim we should be more worried about the regular flu. The expert consensus on this subject isn't currently clear. But as I mentioned at the top of this post, I do think this is the sort of thing where we humans tend to overreact on average, but greatly underestimate the tail (bad scenario) risk.

To reiterate what I said before: we really don't know at this point what's going to happen with the virus. Hopefully, the information above can help you decide whether you think it's serious enough at this point to start any preparation.


Suppose that, considering the information above, you decide it is time to make some preparations to help you protect you and your loved ones, in case the virus does get out of control in your area. What should you do?

Well, I'm no expert, so I'll relay what says you should do to prepare in the event of a pandemic, quoted verbatim:

  • Store a two-week supply of water and food.

  • Periodically check your regular prescription drugs to ensure a continuous supply in your home.

  • Have any nonprescription drugs and other health supplies on hand, including pain relievers, stomach remedies, cough, and cold medicines, fluids with electrolytes, and vitamins.

  • Get copies and maintain electronic versions of health records from doctors, hospitals, pharmacies, and other sources and store them for personal reference. Get help accessing electronic health records.

  • Talk with family members and loved ones about how they would be cared for if they got sick, or what will be needed to care for them in your home.

  • Avoid close contact with people who are sick.

  • When you are sick, keep your distance from others to protect them from getting sick too.

  • Cover your mouth and nose with a tissue when coughing or sneezing. It may prevent those around you from getting sick.

  • Washing your hands often will help protect you from germs.

  • Avoid touching your eyes, nose, or mouth.

  • Practice other good health habits. Get plenty of sleep, be physically active, manage your stress, drink plenty of fluids, and eat nutritious food.

If the things above are not hard for you to do, you may even just want to go ahead and do them for the sake of some peace of mind. Having a long term store of food and water is not a terrible idea anyway, since even under more typical circumstances the water can go out temporarily, or a city can have an extended blackout where shopping becomes difficult (I've been through a few of those in NYC myself!).

If you do choose to take some precautions, I'll also add that it may be a good idea to wash your hands immediately whenever you get home, and to carry hand sanitizer with you when you're in areas with lots of germs (e.g., riding the subway).

Some people have also recommended buying surgical masks, which might be useful if you are forced to go into areas with lots of people during a scenario in which COVID-19 has become widespread. That being said, the usefulness of this strategy is debated, and surgical masks require proper use to be effective at preventing disease.

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