How Many Hospital Beds Are Enough?

The point of “flattening the curve” of coronavirus cases and the “shutdown” happening around the US is to make sure we don’t overwhelm the hospital system. If we let up, is that going to happen?

The answer depends on three numbers: the number of people who will be infected, the number of people who will need hospitalization, and the number of hospital beds available. The first two are both unknowns, so experts are using data from China and projections based on models to make guesses. The third can be estimated. In this essay, I make use of projections epidemiologists and public health experts are using, as well as current hospitalization levels in the US, to get a sense of plausible caseloads that may face hospital systems over the next year, specifically in the service area where I live, to see if they will be overwhelmed.

Epidemiology professor Marc Lipsitch has projected that between 20% and 60% of people will be infected globally—a huge range. Public health experts and commentators like Ari Schulman are settling on a “moderate” estimate that, absent significant collective measures to reduce the spread, the disease will infect about 40% of us. In terms of hospitalization, a common estimate is that about 20% of us will need to go to the hospital.

Thomas C. Tsai, Benjamin H. Jacobson, and Ashish K. Jha, researchers at Harvard’s Global Health Institute, conclude in Health Affairs that, based on these projections, the hospital system will be overwhelmed over the next year, even with some flattening of the curve, facing an overall caseload far exceeding capacity. There are different predictions if the infection prevalence is only 20%. If that the lower bound is realized and the curve is flattened, such that cases are spread out over a year as opposed to concentrated in the initial six-month period, then they predict that US hospitals can handle the caseload with current capacity.

Annie Waldman, Al Shaw, Ash Ngu, and Sean Campbell at ProPublica have generated heat maps visualizing these results. These maps show the percentage of available hospital beds that will be filled across the country in nine different scenarios, varying by both the infection prevalence (20%, 40%, and 60%) and temporal concentration of cases (6, 12, and 18 months). Orange and red are bad, indicating that caseload exceeds capacity in a region. If 40% infection prevalence or higher occurs, at least some regions of the country are overwhelmed, and it gets worse as cases are temporally concentrated and infection prevalence increases.

So where do these projections come from? The 40% infection prevalence estimate, the mid-point of Lipsitch’s projection range, is based on modeling that draws from previous viral epidemics. The 20% hospitalization rate is based on the percentage of people who needed hospitalization in China as of February 24. Near as I can tell, it comes from adding up “critical” and “severe” cases to that point.

There is reason to think the 20% estimate, based on the initial outbreak in China, might be too high. The percentage of people who tested positive for the virus that had been hospitalized in the US was 12% as of March 16, according to the CDC. In New York the figure is 13% as of March 23, according to NPR. Even that percentage might be higher than overall hospitalization rates end up looking, since it only includes people who have tested positive in the denominator. I would expect it to decrease as testing increases. This is a key figure to watch.

Hospital capacity varies by region, so this analysis has to be done at the city or county level. Data and analysis that a team of people from Harvard’s Global Health Institute, ProPublica, and the New York Times put together enable us to do this. You can view the full dataset with the state as the unit of analysis here, with predictions regarding overload based on different levels of infection prevalence and the 20% hospitalization estimate.

Waldman, Shaw, Ngu, and Campbell let us see what this means at the level of Hospital Referral Regions (HRRs). To show you how I’m thinking about this, I use Bryan, TX where I live. The Bryan HRR also includes College Station, home of Texas A&M University, and some surrounding areas. The HRR has a population of 292,000 and a total of 580 beds. Of those, about 45% were occupied as of 2018, leaving 320 available (55%). That’s important—other illnesses and medical needs won’t take a break over the next year. Bryan’s percentage of occupied beds appears to be low—the average occupancy rate around the country is around 64-65%. About that percentage of the Houston HRR’s beds were occupied already, and about 79% of New York’s. Even though there is a lag, this data accounts for other medical services that hospitals will be called on to provide.  

So, the unoccupied 320 beds in the Bryan HRR leave 116,800 available bed-days over the course of one year, 365 days. To break even—to be able to give everyone who needs a hospital bed 12 bed-days, which is the average stay for hospitalized patients in China—the number of people requiring hospitalization over the course of the year from coronavirus would have to be about 9,733, evenly spread out. That’s the magic number.

What follows is a series of rough-and-ready calculations of how many beds the Bryan HRR will need over the year, assuming cases are evenly spread over a year, but with different infection and hospitalization rates. I compare the caseload for these scenarios to the break-even number. Spoiler: if the middling infection prevalence of 40% is right, the virus will overwhelm the Bryan HRR’s available hospital beds. That’s true even with a 12% hospitalization rate. On the other hand, if infection prevalence is only 20%, and the hospitalization rate is 12%, the Bryan HRR is in the clear.

I am not quite sure how the ProPublica analysts come up with estimates of how many people will need hospitalization. The text of the article suggests they are using the 20% hospitalization estimate, but in reporting results for HRRs, they estimate 8% of the adult will need a hospital. I simply take the 20% estimate and apply it to the entire number of infected people.

If 40% of the population gets infected over the next year, that’s 116,800 people. (It’s just coincidence that it’s the same as the number of total bed-days available.) If 20% of those infected will need hospitalization, that’s 23,360—well above the break-even number of 9,733. We need 280,320 bed-days over the year, so we’re short by 163,520 bed-days, or 448 beds (bed-days/365 days). We need to more than double the beds, in fact.

But what if the hospitalization rate is 12%? Now 14,016 people need to be hospitalized over the next year, for 12 days. That’s 168,192 bed-days. We’re still exceeding capacity by 51,392 bed-days, short about 140 beds. Closer, though.

What if 20% get infected, and 20% of those need hospitalization? Now 58,400 people have the virus and 11,680 need to be hospitalized. Still too many, short about 64 beds.  

Finally, the good (well, better) news: if 20% get infected and only 12% need hospitalization, that’s 7,008 needing hospitalization. The Bryan HRR should be fine.

According to the modeling, that’s an optimistic prediction. It relies on a lower hospitalization level than many experts are using, albeit one I think is reasonable.

I made similar calculations for the Houston HRR, and that megacity would still exceed hospitalization capacity with these lower bounds. With 20% prevalence, Houston would need the hospitalization rate to be about 9% to break even. That’s not out of the realm of possibility, but is lower than the most recent figure from the CDC.

This analysis is blunt, and there are a number of limitations—in addition to the fact that I’ve only looked at a couple of cities. It doesn’t differentiate by age group, which will matter because people over 60 are more likely to need hospitalization. It doesn’t account for temporal variation in hospitalization rates; what if we get a sudden upswing in a month? There are also other elements of hospital capacity that will be crucial for this virus, related to ICU beds and ventilators. One other tricky factor is that higher infection prevalence might also decrease capacity, not in terms of beds but in terms of staff if they get infected.

The question naturally arises as to whether there is a connection between the shutdown and the infection prevalence level.

Importantly, all of the above assumes we can’t add or free up more hospital beds or boost capacity in other ways, which state governments are already working on, by adding beds or postponing elective surgeries. That’s a ‘good’ limitation, albeit of little comfort in places like New York, where Governor Andrew Cuomo is reportedly mandating hospitals to increase bed capacity by 50% or more out of desperation.

With all these limitations and caveats in mind, I think we can draw some tentative conclusions. The coronavirus, if it acts like many experts are saying it will, presents a serious challenge in terms of hospital capacity. If the predictions of 40% prevalence and a 20% hospitalization level hold, Schulman and others who say we have to keep the shutdown going for a while are on solid ground in that we can expect hospitals to be overwhelmed if we don’t mitigate the spread, add more capacity, or both. If, on the other hand, the more optimistic predictions are right, lots of HRRs will probably be okay. If the spread of the virus tends toward the infection rate of 20%, the lower bound of Lipsitch’s projection, and hospitalization rates are low enough, US hospitals should be fine, even in heavily populated areas like Houston.

The question naturally arises as to whether there is a connection between the shutdown and the infection prevalence level. How crucial is a prolonged shutdown to pushing the prevalence rate to 20% and spreading out the cases over the year? If it’s crucial, how long would a shutdown have to last to be effective? I don’t know the answers. From what I can tell, the prevalence estimate of 40% is based on assumptions of very limited mitigation efforts. The Harvard researchers seem to think that pushing prevalence to the lower levels may require sustained efforts in the early days to ensure social distancing. Ultimately, we don’t really know what the effect of the shutdown is on the infection rate and the curve, since we do not know the infection rate.

Is there a via media? Could we keep the infection rate down while allowing more economic activity to occur, by maintaining social distancing short of shelter-in-home or lockdown and keeping vulnerable populations at home? That seems plausible, but I don’t know. If we go that route, we should boost hospital capacity. While this analysis is not dispositive of when and how to open the economy, it does give us reason to think the virus could overwhelm US hospitals’ current capacity. Unless optimistic projections are realized, continued measures to reduce spread, boosting hospital capacity, or both will be required to prevent caseload from exceeding capacity.

Reader Discussion

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on March 27, 2020 at 08:33:09 am

The question is, if it is not possible to contain or eradicate this virus, for we have been told, like the flu, most of those who get this virus, will, like the flu, be mildly affected, why try to isolate and contain a whole Nation rather than isolate and protect the elderly, infirm, and those susceptible to infections?

The number One Reason not to isolate those 80% of the population who will have mild to moderate symptoms is so that they can build up immunity.


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on March 27, 2020 at 10:25:33 am

This is a most intriguing analysis. Thank you, Mr. Peterson for your intelligent, hard work.

Yet, the tactical value of statistical models for scenario projection, protective-reaction planning and proactive public health mobilization depends on: 1) possessing an abundance of material data, which we now lack (especially as to the number of infected and the rate of infection) and 2) on making various strategic assumptions, which must of necessity be arbitrary.

So, for Americans our defensive war against "Red China's War on World Health and Stability" will be a tortuous, stumbling, at times near-blind journey in which " We shall not cease from exploration (but) the end of all our exploring will be to arrive where we started and know the place for the first time."

Really, we must acknowledge that only after the plague will we know for the first time where we have been.

But the medical and economic uncertainty and the nation's debilitating existential angst can be greatly mitigated by the widespread deployment of anti-viral medications. They may well save the nation. They can serve to vastly expand the use of doctor/ nurse practitioner-supervised prescription medication and home-based rehabilitation. They may even serve as prophylactic for the immunity-impaired and the vulnerable elderly. That redistribution of medical talent and material would greatly blunt the need for hospitalization and solve the myriad personnel, material, medical device and other hospital-related shortages.
These anti-virals are extremely promising and appear to be on the horizon.

Pray God they are the sword with which we can wound Red China's Apocalyptic Dragon while we master the science of how to kill it.

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on November 16, 2020 at 13:49:22 pm

“Pray God they are the sword with which we can wound Red China's Apocalyptic Dragon while we master the science of how to kill it.”

First thought, figure out how to treat inflammation by “making use of the already- established literature on the interplay of local and systemic iron regulation, cytokine-mediated inflammatory processes, respiratory infections and the hepcidin protein.



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on March 27, 2020 at 12:05:48 pm

The USA needed over 12 million soldiers to wage WW2. They were created as and when needed and when that was done, those armies were disbanded. Why weren't they already there on Dec. 8, on standby, together with all of the ships and planes needed to transport them and all of the weapons for them to fight with etc.? Or, what if those armies had been maintained afterwards in order to meet the next war? If all these thousands of ICU beds and ventilators are added during this crisis, what becomes of them when no longer needed? Who pays for their maintenance? What if the next virus attacks the kidneys and instead of ventilators we need thousands more dialysis machines? Maybe we should start stockpiling dialysis machines now just in case. We've been in this thing for just 3 weeks really and all people can do is make more or less shrill demands that the government should have been adequately prepared to instantly take over everything and get all necessary resources and supplies to everywhere they are needed within a week. They sound as though they really believe that we can build and maintain all that slack in the health care system, ready to be taken up at a moment's notice: thousands of ICU beds and ventilators and other machines and equipment just stored somewhere, always on standby. That's not how economies operate. That's why we have no warehouses overflowing with toilet paper and hand sanitizer sufficient for 350 million people for a year. Even the nationalized European healthcare systems don't have enough beds or ventilators. In no system can you maintain enough slack so that the system will not be overwhelmed in a crisis. It's like the war movies where half the platoon is gunned down and everyone is shouting "Medic!" and there are only a couple of medics. Why doesn't the army equip each platoon with 30 medics at all times?

Many people also believe that all this could somehow have been avoided by a coterie of bureaucrats titled "pandemic response team," as if this crisis is upon us for want of senior level bureaucrats issuing out orders to other bureaucrats. So far as I know, our president did not "disband" any European pandemic response team. So why is Europe in crisis?

When this crisis is over it will be the "last war" and we should not fight the last war. Unless and until better treatments and cures for viral infections come along (which is probably where all the money should be invested), there is no policy that can adequately predict and prepare for the next virus war, or at least not with any reliable chance of success except dumb luck (i.e., luck in predicting the specific actions of the next virus and the materials that will be needed to deal with it). Laws and regulations designed to force us all into our homes the instant some expert or other delivers a worst-case model for the next new virus discovered somewhere? No thanks.

People are just upset at being reminded of their (our) biological structures, weaknesses and limitations. Once again, Nature is on the attack. As Horace said: you can drive Nature out with a pitchfork, but she always returns.

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on March 27, 2020 at 17:06:40 pm

Interesting observation.

By virtue of their thin psychological nature Dem's are irresponsible scapegoaters, always looking to blame others for a crisis and especially for their own failings (just observe deBlasio and Cuomo,) while political leaders generally mistakenly plan to fight the last war or prepare to respond to the last natural disaster, only to be confounded by a new military strategy and an unanticipated natural calamity.

Hurricane response and vaccinations seem the only exception.

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on March 27, 2020 at 14:32:21 pm

And now for some good news to counter the rampant hysteria based, of course, upon the media's vaunted ability / propensity to analyze and promulgate "scientific" data. It comes from my neck of the woods (now known as Hobbittown).

One excerpt"

" In the state that saw the nation’s first confirmed covid-19 case on Jan. 31, and the first recorded coronavirus-related death on Feb. 29, initial dire predictions of massive spikes have waned even as testing has increased rapidly. While the number of cases in Washington state grew by as much as 28 percent in one day on March 15 — it has since slowed significantly statewide, as have hospitalizations and deaths.

State authorities said there have been 2,580 positive cases and 132 deaths, and as testing in Washington has ramped up, the percentage of positive cases has remained low — holding at about 7 percent. "

No doubt this improvement must be related to the Governors decision to ban fishing due to reports that there may have been as many as four people on a boat launch ramp and to close golf courses.
Yep, that must have been it!

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on March 27, 2020 at 16:43:15 pm

Where does Washington State find its whacko political leaders? Is the water west of the Cascades hallucinogenic? Are 95% of the sane people east of the mountains?

I remember when your state had excellent Governors and fine Senators, like Warren Magnuson, Scoop Jackson and Slade Gorton (whom I admire especially because in Senate testimony he once described my answer to his question on the Safe Drinking Water Act as one of the smartest answers he had heard.)

Washington needs more statesman- politicians like that, men and women who agree with you and me.

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on March 27, 2020 at 18:28:59 pm

1) It is 98% of the sane people that live east of the mountains!
2) the waters of the Puget Sound are indeed hallucinogenic. They must be as, contrary to all evidence, I continue to think that I live in a sane community. I should stop swimming with my mouth open.
3) Slade accepted a position as Partner Emeritus with my wife's law firm. A rather reasonable fellow who, however in his dotage has shown some incipient signs of "wokeness" - no doubt in response to the typical law firm milieu.
Still, however, one of the better representatives of this once great state along with Scoop and Magnuson. Contrats them with a socialist Seattle city council and a Malcolm Milquetoast of a Governor however recently disposed to demonstrate his Progressive (re: totalitarian) bone fides and one garners some measure of the decline of *politics* properly understood in the Pacific Northwest.

Were it not for family, in particular grandchildren, I would flee to the southeast and be done with this idiocy.

Now back to my Hobbit hole and like Bilbo, I am well stocked with Washington wines, food and may make myself invisible again.
Oops, I forgot, Malcolm Milqutoast has stolen the One ring to Rule them All.

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on March 28, 2020 at 11:02:35 am

Gorton's ''wokeness" may, perhaps, be reflected in what I see from an internet search appears to be his association with the Ruckelshaus Center, whose late founder, nearly 50 years ago, was my employer (so to speak) as head of US EPA and even then among the Republican Party's elite "wokesters."

His ban of DDT was arbitrary, contrary to facts and science and over-ruled the decision of the administrative law judge who spent weeks hearing the evidence. That ban in the US sparked a world-wide ban of DDT which, arguably, over the ensuing decades cost the lives of millions of people in the third world, mostly children.

Wokeness then and now doth have its price.

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on March 28, 2020 at 11:15:36 am

Knowing that you are blessed with oenophilia while suffering house arrest during the "Red China War On World Health and Stability," I offer this as a means of staying mentally and physically fit:

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on March 27, 2020 at 16:07:31 pm

During the 2017-2018 influenza season there were 61,000 deaths in the United States. How many of these were on a ventilator? Was it all 61,000? If not, why not? What criteria were used to determine which influenza patient who would ultimately die would not be place on a ventilator? Assuming that the 61,000 were from a population that included those who were very sick, who could have gone either way but did in fact recover, how big was that population? 122,000? Why didn't this population overwhelm the medical system?

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on March 27, 2020 at 18:34:22 pm

"Why didn't this population overwhelm the medical system?"

Because the media did not "want" it to do so.

Important to note as you allude to that these sort of determinations are made EVERY single day and in every single "plague" that we experience. Cui bono?
Why is it only now that our media friends highlight this critical contrived "shortage"?

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on March 28, 2020 at 14:27:19 pm

The author completely misunderstands the shutdown. The issue is not the covid-19 virus, rather it is the people rushing the medical system the same way they rushed the toilet paper aisle and the terrible effect that has.

A relative of mine is a nurse practitioner. She works with cancer patients. She finds herself overwhelmed, working 12 hours days to address the illness. Which is amazing given that covid-19 hasn't arrived in her area yet!

A lot of her patients are approaching her to get more information about the virus, which is what adds a lot of time in her day. Other people are coming in for really weird reasons. The way she describes it, "There are so many nuts out there we need to bring in some squirrels to direct traffic."

Her office is out of medical masks and almost out of medical gloves. The few masks that are left in her hospital system are reserved for surgeons. Non-medical people are hoarding them for personal use, and I imagine that the masks probably come from China which has slowed down production of masks and everything else due to fears of the virus.

Medical masks are important for medical staff because they come in contact with every fluid and substance that comes from the human body. Those excretions frequently have germs and viruses from diseases that are much, much worse than covid-19. That's why the patients are seeking medical help. Once a medical staffer becomes sick from those diseases, the staffer spreads the disease to other patients. The other patients are often people who have compromised immune systems, which makes them more susceptible to diseases. The masks help keep the staff from getting nastiness sprayed, squirted, coughed, dripped, smeared, etc onto their faces where diseases have easy access to the body.

Keep in mind that hoarded medical masks do not prevent people from getting the covid-19 virus.

A lot of young and healthy Italian doctors are getting sick and dying from the virus. The thing that stands out about their situation is that they are working to exhaustion. When exhausted the body is less able to fight and recover from diseases.

I don't know what goes on in the Italian doctors' workplaces, but I can reasonably assume that just as my relative is being overwhelmed with covid-19 related panic (when the disease hasn't yet arrived in her area), the Italian doctors are being overwhelmed by more than just the disease. They are dealing with the consequences of the panic more than they are dealing with the disease.

And that is the point of shutdown. The panic is the problem more than the disease is.

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Scott Amorian
on March 29, 2020 at 07:00:14 am

Blessed with oenophilia while suffering house arrest during the "Red China War On World Health and Stability," I offer this as a means of staying mentally and physically fit:

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on March 29, 2020 at 07:11:12 am

This note was written originally as a reply to Gabe, but it strikes me that we all need this now:

Blessed with oenophilia while suffering house arrest during the "Red China War On World Health and Stability," I offer this as a means of staying mentally and physically fit:

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on March 29, 2020 at 21:26:44 pm

I asked above why the healthcare system was not overwhelmed in 2017-2018 when there were 61,000 influenza-related deaths, and one may assume a significant number of near-deaths. While Gabe gave a typically thoughtful answer, I wanted to remark on another factor. Consider the following:

An 85 year-old patient with a history of metastatic breast cancer, heart disease, emphysema and diabetes gets admitted to the hospital for repair of a broken hip. During the initial patient encounter the physician asks if the patient wishes to be resuscitated if her heart were to stop, or if her breathing qqould deteriorate to the point that she would need to be on a ventilator. The patient responds "no," and requests to be made "Do not resuscitate," a decision with which the family agrees. The physician nods understandingly and asks, "What if your heart were to stop because a nurse gave you the wrong medicine, or wrong dose by mistake?" In the circumstances, the patient and family would want resuscitation.

Our sense of the inevitability of death seems to come with an asterisk. We know we are going to die, maybe soon, and maybe even that, all things considered, it is not a bad thing, But we have an aversion to what is perceived as dying needlessly. Catholics used to ask the Virgin Mary for "a good death," and that is understood as an ideal. That ideal usually does not include someone else's bumbling. We don't become overwhelmed by influenza because dying of influenza, considering history or its familiarity or combination of expectation and resignation, is considered a natural death. It is part of the "natural shocks that flesh is heir to." Coronavirus is not. Because of its novelty, suspicious origins, media hyping it as an avoidable crisis, etc. dying of coronavirus is not part of accepting death gracefully. It is seen as an unnatural and perhaps even sinister way of dying. The notion is that coronavirus must be resisted at all costs, even if the life expectancy of the patient might have been measured in months, even without ever encountering COVID-10

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on April 03, 2020 at 13:22:55 pm

This comment may be a little late BUT:


wherein we observe the media's usual and also as usual successful efforts to overreact and scare the living bejesus out of the populace while employing such methods as portraying an Italian hospital's chaos as a New York city hospital. There is more. Worth the 10 minutes or so.
execrable methods by an exceedingly execrable contingent.

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on August 13, 2020 at 15:06:24 pm

A recent study has shown that low population density in some states has acted to limit spread of Covid-19 and hence the capacity shock, see https://www.mdpi.com/1660-4601/17/14/5210/pdf

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Rodney P Jones

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