Running the Numbers on Coronavirus in America

Health care workers in protective suits, Wuhan China. Photo credit: China Daily / Reuters

By DJ Rippert

Sprichst du panik? Liz Specht is an biologist and engineer. She is currently the Associate Director of Science and Technology at The Good Food Institute. On Friday Dr. Specht (who holds a Ph.D. from UCSD) posted a long series of tweets regarding the spread of Coronavirus and the limitations of America’s healthcare system. You can read her tweets here.

Dr. Specht is vitally concerned about COVID-19 and the supply of hospital beds and protective masks in the U.S. She calculates that by May 8 all the hospital beds in the U.S. will be filled. That’s just over two months from now. She further believes that America’s low inventory of N-95 and surgical masks required for healthcare workers will only make matters worse. As those tending to COVID19 patients get sick we may run out of healthcare workers as well as hospital beds.

This may differentially impact Virginia. As Bacon’s Rebellion guest commentator James C Sherlock noted, Virginia has a shortage of docs and nurses. In addition, experience in Italy shows that up to 10% of cases which tested positive required mechanical ventilators as part of the treatment. Whether Virginia’s very questionable COPN practices have held down the number of hospital beds and / or mechanical ventilators is an open question. Meanwhile, as Jim Bacon notes, our state government’s reaction to COVID-19 is somewhere between “just trust us” and “what, me worry?”

Very important note — Dr. Specht is a trained biologist who certainly holds some strong opinions as to the public health severity of COVID-19 in the United States. However, she is not an epidemiologist. Other equally expert people, including some epidemiologists, do not share her pessimism. The crux of Specht’s argument is that the number of Coronavirus cases will double every six days. I have no idea whether Dr. Specht will be proven right or wrong on that count. I do know that if she is right, Virginia is in a world of trouble.

The essential math. In the 24th (!) tweet in her chain Dr. Specht writes, “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 frequently find myself doing the same thing. Let’s look at Dr. Specht’s math.

  1. On March 6 there were approximately 250 confirmed cases of  COVID-19 in the US.
  2. America’s lack of test kits means that there are far more cases than have been detected to date. Specht uses an 8X multiplier to get 2,000 actual cases as of March 6.
  3. Using epidemiological methods and models, Specht sees the number of cases doubling every six days. Confirmed cases may appear to rise even faster as more test kits are rolled out.
  4. This exponential progression calculates one million U.S. cases by the end of April, two million by May 5, four million by May 11, etc.
  5. The virus will continue to expand exponentially until it has infected more than 1% of the “susceptible population” at which time it may slow. Specht never defines “susceptible population,” but I assume all Americans are susceptible.  That generates 3.3 million infections before the spread even slows.
  6. Using Italy as a guide, 10% of those infected will require hospitalization. That leaves us with a need for 330,000 hospital beds before the presumed pandemic even slows.
  7. America has about one million hospital beds; 65% are typically in use at any given time. That means 350,000 open beds although the “regular flu” this time of year might push utilization above 65%.
  8. Even if every open hospital bed in the U.S. is suitable for the isolation of patients with infectious diseases, the hospitals will be full by May 8th.
  9. As the hospitals fill, the demand for doctors and nurses will also increase. This brings up the question of protective masks for health care workers.
  10. There are 18 million healthcare workers in the U.S.. The U.S. has a “stockpile” of 12 million N-95 masks and 30 million surgical masks.
  11. Once the virus starts to spread in earnest, every working health care worker will need a mask. Using the conservative assumption of one third of health care workers treating patients each day and the more conservative assumption of using one mask per day the supply of masks will run out in two days. (Note: I cannot follow Dr. Specht’s math here: 42M masks / 6m health care workers on a given day = seven days of supply, not two.)
  12. Almost all masks used in the U.S. are manufactured overseas, mostly in China. Even the raw materials for masks come from outside the U.S., mostly from China.

Margin of error. Dr Specht allows that her estimates may be wrong. She writes, “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.”

Earth to Ralph Northam … Governor Ralph Northam’s message to Virginians can be summarized as “don’t worry, we’re ready.” This lacks credibility and should be seen as completely unacceptable. When biologists like Dr. Specht put forth harrowing numbers like those in her tweet stream Virginians need more than “trust me” from our already credibility-challenged governor.

Correction: The article originally misidentified Dr Specht as an epidemiologist. That is incorrect. While Specht is reported to hold a Ph.D. in biology she is not described as an epidemiologist.