I have been getting lots of requests for my opinion about where we are and what is coming.
The first question is: How bad will the coronavirus epidemic be in the U.S.?
The short answer is, we don’t know – but it could be pretty nasty. An important point, though, is that we are not helpless here. This is not like predicting a weather event where we cannot control where the hurricane goes or how strong it is. Our individual and societal behaviors will have a big impact on what happens.
The second question is: How much are we willing to do (as individuals and as a society) to mitigate the threat?
Before we can begin to address either question, we need to set some context.
The case fatality rate (CFR) is the number of deaths among those officially diagnosed with coronavirus because they are sick enough to seek medical attention, and they and their medical providers are able to access testing. Current best estimates based on data from other countries like China are a CFR of 2 to 3 percent. This is 20-30 times as deadly as influenza (which kills ~ 30,000 Americans every year) and, since coronavirus appears to be quite easily spread, this is very bad. But …
The infection fatality rate (IFR) is a more important figure because it represents the number of deaths among all those who are infected. Here, the denominator includes large numbers of individuals who have minimal symptoms or no symptoms. The best current estimates of the IFR are 0.15 percent. This is three times higher than seasonal influenza and still a serious problem.
The transmission of coronavirus is related to the duration and intensity of the contact. It is significantly more likely to spread than seasonal influenza. The current evidence-based projections are 25 million to 115 million Americans will be infected with coronavirus over the next 6-12 months. This would mean 350,000 to 660,000 deaths in the U.S. (Note, this is very, very hard to estimate, and the uncertainty range is probably 50,000 to 5 million deaths.)
Now, let’s talk about what we can do as individuals and a society to mitigate this.
As individuals, we can limit our personal risk in many ways. We can wash our hands with warm water and soap frequently and use hand sanitizer with 60 percent alcohol when soap and water are not available. We can avoid crowds (over some arbitrary number like 100 or 500) and close or prolonged contact with groups that are smaller than crowds (over 10, perhaps). We can avoid exposure to people likely to be vectors: Don’t travel, don’t hang out with friends who want to show you their slides of their trip last week to Italy. Don’t hang out with people who work in hospitals or have lots of contact with large numbers of people. We can shop at low volume times. We should stop touching our faces – but the evidence is that we can’t. How much will this lower our individual risk? It’s impossible to quantify, but it is probably significant. We should remember back in the early days of AIDS when we told people that, when they had sex, they were actually having sex with everyone their partner had had sex with. When you go to a party, you are being exposed to everyone that all the attendees have been exposed to. If you invite people to an event, you are actually inviting exposure not just to the attendees, but to everyone the attendees have had contact with for the previous two weeks.
As individuals, how can we reduce our contribution to societal risk? All of the things that reduce our individual risk will also reduce the likelihood that we become a vector and spread coronavirus. Even if we are not very concerned about our personal safety, I would argue that we should be aggressively acting to protect ourselves because that protects others.
What can our social and government structures do? First, the U.S. is not like Italy or Germany or the areas in many, many ways. We should not expect a monolithic epidemic here. Instead, we should expect multiple local outbreaks and epidemics with patterns related to local contexts, at least initially. To a large degree, this means that local and state health departments are key, not a federal response. (And we have excellent evidence that, at the Federal level, science and public health are not the drivers at this time.)
There is good evidence from past epidemics and already from our experience with coronavirus that aggressive social distancing flattens the curve and saves lives. The later it is instituted, the more extreme it needs to be in order to work. One of the reasons this approach makes a difference is that, once the health care system is pushed past its optimal capacity (and in the U.S., financial pressures mean that we operate close to optimal capacity at baseline to avoid having to pay for empty beds and personnel with nothing to do) the system ceases to be able to adequately identify and treat other health problems. (If 10 to 15 percent of health care workers have to self-quarantine, a very modest estimate, hospital capacity drops much more than 10 to 15 percent.) This means that, in addition to the deaths projected above from coronavirus, one gets ‘excess mortality’ or deaths from otherwise treatable things like heart disease, kidney disease, trauma, cancer, and the like.
So, we should expect and accept very extensive cancellations of public events, banning of audiences at sports events, a transition away from live interactions to virtual interactions, school closures, videocasting instead of live attendance at meetings. For how long? I don’t think we know, but probably for 4 to 6 months and possibly for a year.
And, as a parting thought, consider the tipping point concept. If we don’t act before it is obvious that we have to, we may be too late to make a difference.
That’s my story, and I’m sticking to it. At least for 24 hours, when new and better information will surely change some or all of what I wrote.
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