[Edit, March 2 14:27 PST: Rewrote analysis on hospital capacity, clarified definition of “mild” symptoms, and infection impact on children.]

The purpose of this essay is to persuade you (or a friend or loved one) to take your personal coronavirus (“COVID-19”) preparations & practices seriously. It is a bit US-centric; apologies to any non-US readers.

It can be quite difficult to gauge the severity of the situation, as there are as many people saying “it’s fine!” as there are saying the zombie apocalypse is upon us. And I’m not just talking about our social media feeds — I’m talking about things like POTUS and the WHO contradicting each other on key facts. I hope this essay can cut through some of the confusion.

I don’t think the zombie apocalypse is upon us, but I also wouldn’t say things are “fine” — I think we’re facing a level of risk that is quite serious, and warrants prompt personal preparation and care.

Some acknowledgments: I do not have professional experience in this area. This is a complex topic, and my analysis may be flawed. I welcome corrections or other interpretations / insights down in the comments.

Severity

The good news is, as you may know, ~85% of COVID-19 infections have moderate, mild or occasionally even no symptoms. (“Moderate” here is relative, and can include things like pneumonia.) It also appears to have limited impact on children under age 10, with much milder symptoms and no fatalities reported so far.

However, ~15% of infections are severe enough to require hospitalization, often requiring mechanical ventilators (one of the symptoms is shortness of breath).

Infection fatality rate (# of deaths / # of infections), or IFR, is very hard to estimate early in an outbreak, because it is hard to count deaths (many infections have not yet resolved either way), and it is hard to count infections (it’s hard to test everyone). Many of the numbers you see in the news (like the WHO’s oft-cited 3.4% from a couple of days ago) are not correcting for these factors; they’re just taking “# of deaths to date” / “# of confirmed cases to date” (you can confirm this calculation yourself here), so can be misleading.

Nonetheless, some fairly sophisticated analyses have tried to account for these factors. Here are two: 1 2. (The first was cited by the WHO in one of their publications.) These papers both estimate an IFR of ~0.9%, with high uncertainty (95% confidence interval ranges from ~0.3% to ~3.0%.)

Obviously any fatality rate over 0 is bad, but how bad are we talking? Well, seasonal flu has a fatality rate of 0.1%. H1N1 (aka swine flu, the pandemic from 2009) had a fatality rate of 0.01–0.08% — let’s call it 0.05%. So in terms of fatality rates, COVID-19 is currently 6–60x worse than H1N1, and 3–30x worse than seasonal flu.

It’s important to note that fatality rates vary substantially with age (older = more risk), and with the presence of complicating factors (respiratory issues, being immunocompromised, etc.). Importantly, some early analysis suggests that the 15% chance of hospitalization might not vary with age, so all of us (except young children) would be at risk of severe illness if we caught COVID-19.

Spread

There are a lot of nasty infections in the world, but they only need concern us to the extent we’re at risk of catching them. So what is the risk with COVID-19? This is also a very complicated question, but here are three different data points:

During the initial Wuhan outbreak, the number of reported cases was doubling every 3–5 days for a couple of weeks. (You can look at the raw numbers here.) That’s assuming China’s numbers are trustworthy; given some of their early efforts to cover up the outbreak (example) they could be underreported.



We might say: Maybe COVID-19’s fast spread in Wuhan was a fluke, due to some unique conditions in that city, or the virus being new and catching them by surprise. Maybe. But so far, the growth curve for non-China cases is similar to the growth curve for China cases (compare the yellow and orange lines here). This (annoyingly overdramatized) video compares the growth rate of various pandemics. While it’s still very early, COVID-19’s growth curve is about as steep as H1N1’s, which went on to infect ~10–20% of the global population, including ~20% of Americans. Here is an analysis from Marc Lipstich, Director of the Center for Communicable Disease Dynamics at Harvard. This analysis was retweeted (i.e. implicitly endosed) by Scott Gottlieb (former Trump FDA commissioner). Mr. Lipsitch’s analysis is that 40%+ of adults worldwide could catch COVID19 in the next year “in a situation without effective controls”.

As of this writing, there are 233 confirmed cases in the US. But that is certainly underreported. COVID-19 testing in the US has been extremely slow, due to FDA regulations (finally loosened this past weekend) and flawed CDC test kits. (As recently as Monday, the CDC reported a total of only 472(!) tests performed nationwide.)

So how many US infections are there really? That’s a very complicated question, but when you consider (1) the lack of testing, and (2) the fact that people can potentially spread the disease for several days before showing symptoms, it seems likely the actual infections number in the thousands.

As mentioned above, the US currently has 233 confirmed cases. China had ~233 confirmed cases on January 20. 25 days later (that’ll be March 31 for us), they had 66,000. If things continued to double every 5 days, that’s 2m by end of April, and 100m by end of May. Hopefully containment & other mitigation efforts will slow that greatly, but this gives one a sense of just how critical those efforts are.

Note that COVID-19 may be a seasonal disease, like cold/flu. If so, warmer temperatures will help slow the spread. So mitigation in the next few months may be especially crucial.

Mitigation Efforts

Unfortunately, a vaccine is unlikely to be available until 2021.

So, what are other countries doing to mitigate the spread?

China imposed a draconian lockdown on the city of Wuhan (and elsewhere) — they more or less shut down a city the size of NYC, barring all travel in and out of the city without special government permission. This (along with other interventions) was hugely successful — China has seen a ~21% rise in total cases over the past three weeks, compared to a ~7200% rise in the three weeks prior. (Raw data available here)

Italy, with 3,000 confirmed cases, shut down all schools and universities nationwide.

South Korea has set up 500 drive-through COVID-19 testing stations, and tested over 100,000 people. (200x the US.)

Taiwan is a great COVID-19 success story. They are right next to mainland China with heavy travel back and forth, so they were exposed to a lot of risk, yet they have only 44 confirmed cases as of today — and that’s with heavy testing! As soon as the virus was discovered on December 31, Taiwanese officials started boarding incoming flights from Wuhan as they landed, screening passengers before allowing them to deplane. They merge their health insurance and immigration/customs databases, doing analytics to help identify high-risk individuals based on travel history and clinical symptoms. And when a subject is quarantined at home, their mobile phone is used to track their location and enforce the quarantine.

So what’s our outlook here in the US? I wish I could say I was optimistic. But:

I’m skeptical that we have the political will to impose drastic measures like China did in Wuhan.

South Korea opened their first drive-through testing station when they had about 900 cases, but I’ve not yet seen any indications of operational/infrastructure moves like that.

The US government does not have a particularly good IT track record to inspire confidence that we’ll develop technological solutions quickly like the Taiwanese.

Most of what I’ve seen from the US so far has been a slow, bungled testing operation and a government that’s not even internally aligned.

There have been a few promising actions in recent days. Let’s hope there’s a lot more where that came from.

Complication 1: Hospital Capacity

As if all that weren’t bad enough, rapid spread would mean we’ll be at risk of running out of hospital capacity in the US.

In the US, there are roughly ~315k general hospital beds available on average (~931k beds total, ~66% occupancy rate). With a 15% hospitalization rate, 2M concurrent infections will use up all our hospital beds.

And that assumes that all infections and available beds are uniformly distributed around the country, which of course they are not. Infections will spike in some areas, and some of those areas may also happen to have fewer hospital beds available (due to regular seasonal flu outbreaks, for example, or institutional/funding challenges). So localized shortages will happen at much lower levels of concurrent infection. Similar bottlenecks may exist for other hospital resources (mechanical ventilators for acute COVID-19 patients, trained staff, etc.)

Needless to say, hospital shortages would mean higher fatality rates.

Will we hit 2M concurrent infections? It’s hard to say, but the 2009 H1N1 pandemic saw a total 55M infections in the US in a 9-month period. Undoubtedly we’ll be employing stronger containment procedures for COVID-19 (indeed, we already are!); hopefully those are strong enough.

Complication 2: Economic & Social Disruption

With just 233 confirmed cases, many major companies are already encouraging or requiring employees to work from home, and major conferences and trade shows are being canceled. I predict we will soon see fairly severe disruption of day-to-day life. Hopefully this is because the government starts taking strong containment measures (shutting down schools, banning large gatherings, travel restrictions, etc.). To the extent they fail to do that, and the virus spreads fast, absenteeism (whether due to illness or fear) will probably start to hinder companies’ ability to operate.

I also anticipate major second-order effects. Schools double as day care for many families. Travel, tourism, restaurants, and retail industries are going to take a beating (travel has already started to). If absenteeism gets bad enough, we’ll start seeing supply chain disruptions.

I am not predicting apocalypse here; the water and electricity stayed on in Wuhan, and delivery services continued to operate. I think the US will probably be able to manage that as well. But I anticipate significant disruption in day-to-day life for a few months and significant hardship for many people.

How Can You Prepare?

There is a lot we can do collectively to beat this thing. Pandemics require transmission, and we can stop transmission by working together to take the proper precautions.

You have even greater control over your own personal safety, through the precautions you take — and hopefully your loved ones’ safety, if you can convince them to take good precautions too.

Here’s a good community-generated “pandemic preparedness” list.

Coinbase, a financial services company, has written a COVID-19 preparation guide for their employees, and posted it on their blog. It’s one of the most readable & well-rounded ones I’ve seen. Here’s the link — it’s the section titled “Social Distancing Guide”.

Here’s the CDC’s official household COVID-19 prep guide.

Let’s do this!