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Liz Specht
I think most people aren’t aware of the risk of systemic healthcare failure due to because they simply haven’t run the numbers yet. Let’s talk math. 1/n
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Liz Specht Mar 6
Replying to @LizSpecht
Let’s conservatively assume that there are 2,000 current cases in the US today, March 6th. This is about 8x the number of confirmed (lab-diagnosed) cases. We know there is substantial under-Dx due to lack of test kits; I’ll address implications later of under-/over-estimate. 2/n
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Liz Specht Mar 6
Replying to @LizSpecht
We can expect that we’ll continue to see a doubling of cases every 6 days (this is a typical doubling time across several epidemiological studies). Here I mean *actual* cases. Confirmed cases may appear to rise faster in the short term due to new test kit rollouts. 3/n
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Liz Specht Mar 6
Replying to @LizSpecht
We’re looking at about 1M US cases by the end of April, 2M by ~May 5, 4M by ~May 11, and so on. Exponentials are hard to grasp, but this is how they go. 4/n
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Liz Specht Mar 6
Replying to @LizSpecht
As the healthcare system begins to saturate under this case load, it will become increasingly hard to detect, track, and contain new transmission chains. In absence of extreme interventions, this likely won’t slow significantly until hitting >>1% of susceptible population. 5/n
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Liz Specht Mar 6
Replying to @LizSpecht
What does a case load of this size mean for healthcare system? We’ll examine just two factors — hospital beds and masks — among many, many other things that will be impacted. 6/n
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Liz Specht Mar 6
Replying to @LizSpecht
The US has about 2.8 hospital beds per 1000 people. With a population of 330M, this is ~1M beds. At any given time, 65% of those beds are already occupied. That leaves about 330k beds available nationwide (perhaps a bit fewer this time of year with regular flu season, etc). 7/n
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Liz Specht Mar 6
Replying to @LizSpecht
Let’s trust Italy’s numbers and assume that about 10% of cases are serious enough to require hospitalization. (Keep in mind that for many patients, hospitalization lasts for *weeks* — in other words, turnover will be *very* slow as beds fill with COVID19 patients). 8/n
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Liz Specht Mar 6
Replying to @LizSpecht
By this estimate, by about May 8th, all open hospital beds in the US will be filled. (This says nothing, of course, about whether these beds are suitable for isolation of patients with a highly infectious virus.) 9/n
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Liz Specht Mar 6
Replying to @LizSpecht
If we’re wrong by a factor of two regarding the fraction of severe cases, that only changes the timeline of bed saturation by 6 days in either direction. If 20% of cases require hospitalization, we run out of beds by ~May 2nd. 10/n
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Liz Specht Mar 6
Replying to @LizSpecht
If only 5% of cases require it, we can make it until ~May 14th. 2.5% gets us to May 20th. This, of course, assumes that there is no uptick in demand for beds from *other* (non-COVID19) causes, which seems like a dubious assumption. 11/n
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Liz Specht Mar 6
Replying to @LizSpecht
As healthcare system becomes increasingly burdened, Rx shortages, etc, people w/ chronic conditions that are normally well-managed may find themselves slipping into severe states of medical distress requiring intensive care & hospitalization. But let’s ignore that for now. 12/n
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Liz Specht Mar 6
Replying to @LizSpecht
Alright, so that’s beds. Now masks. Feds say we have a national stockpile of 12M N95 masks and 30M surgical masks (which are not ideal, but better than nothing). 13/n
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Liz Specht Mar 6
Replying to @LizSpecht
There are about 18M healthcare workers in the US. Let’s assume only 6M HCW are working on any given day. (This is likely an underestimate as most people work most days of the week, but again, I’m playing conservative at every turn.) 14/n
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Liz Specht Mar 6
Replying to @LizSpecht
As COVID19 cases saturate virtually every state and county, which seems likely to happen any day now, it will soon be irresponsible for all HCWs to not wear a mask. These HCWs would burn through N95 stockpile in 2 days if each HCW only got ONE mask per day. 15/n
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Liz Specht Mar 6
Replying to @LizSpecht
One per day would be neither sanitary nor pragmatic, though this is indeed what we saw in Wuhan, with HCWs collapsing on their shift from dehydration because they were trying to avoid changing their PPE suits as they cannot be reused. 16/n
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Liz Specht Mar 6
Replying to @LizSpecht
How quickly could we ramp up production of new masks? Not very fast at all. The vast majority are manufactured overseas, almost all in China. Even when manufactured here in US, the raw materials are predominantly from overseas... again, predominantly from China. 17/n
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Liz Specht Mar 6
Replying to @LizSpecht
Keep in mind that all countries globally will be going through the exact same crises and shortages simultaneously. We can’t force trade in our favor. 18/n
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Liz Specht Mar 6
Replying to @LizSpecht
Now consider how these 2 factors – bed and mask shortages – compound each other’s severity. Full hospitals + few masks + HCWs running around between beds without proper PPE = very bad mix. 19/n
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Liz Specht Mar 6
Replying to @LizSpecht
HCWs are already getting infected even w/ access to full PPE. In the face of PPE limitations this severe, it’s only a matter of time. HCWs will start dropping from the workforce for weeks at a time, leading to a shortage of HCWs that then further compounds both issues above. 20/n
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Liz Specht Mar 6
Replying to @LizSpecht
We could go on and on about thousands of factors – # of ventilators, or even simple things like saline drip bags. You see where this is going. 21/n
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Liz Specht Mar 6
Replying to @LizSpecht
Importantly, I cannot stress this enough: even if I’m wrong – even VERY wrong – about core assumptions like % of severe cases or current case #, it only changes the timeline by days or weeks. This is how exponential growth in an immunologically naïve population works. 22/n
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Liz Specht Mar 6
Replying to @LizSpecht
Undeserved panic does no one any good. But neither does ill-informed complacency. It’s wrong to assuage the public by saying “only 2% will die.” People aren’t adequately grasping the national and global systemic burden wrought by this swift-moving of a disease. 23/n
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Liz Specht Mar 6
Replying to @LizSpecht
I’m an engineer. This is what my mind does all day: I run back-of-the-envelope calculations to try to estimate order-of-magnitude impacts. I’ve been on high alarm about this disease since ~Jan 19 after reading clinical indicators in the first papers emerging from Wuhan. 24/n
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Liz Specht Mar 6
Replying to @LizSpecht
Nothing in the last 6 weeks has dampened my alarm in the slightest. To the contrary, we’re seeing abject refusal of many countries to adequately respond or prepare. Of course some of these estimates will be wrong, even substantially wrong. 25/n
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Liz Specht Mar 6
Replying to @LizSpecht
But I have no reason to think they’ll be orders-of-magnitude wrong. Even if your personal risk of death is very, very low, don’t mock decisions like canceling events or closing workplaces as undue “panic”. 26/n
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Liz Specht Mar 6
Replying to @LizSpecht
These measures are the bare minimum we should be doing to try to shift the peak – to slow the rise in cases so that healthcare systems are less overwhelmed. Each day that we can delay an extra case is a big win for the HC system. 27/n
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Liz Specht Mar 6
Replying to @LizSpecht
And yes, you really should prepare to buckle down for a bit. All services and supply chains will be impacted. Why risk the stress of being ill-prepared? 28/n
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Liz Specht Mar 6
Replying to @LizSpecht
Worst case, I’m massively wrong and you now have a huge bag of rice and black beans to burn through over the next few months and enough Robitussin to trip out. 29/n
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Liz Specht Mar 6
Replying to @LizSpecht
One more thought: you’ve probably seen multiple respected epidemiologists have estimated that 20-70% of world will be infected within the next year. If you use 6-day doubling rate I mentioned above, we land at ~2-6 billion infected by sometime in July of this year. 30/n
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Liz Specht Mar 6
Replying to @LizSpecht
Obviously I think the doubling time will start to slow once a sizeable fraction of the population has been infected, simply because of herd immunity and a smaller susceptible population. 31/n
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