As it turns out other people than I are also doing back-of-the-envelope calculations about COVID-19 so you don’t just have to take my word for it. Over at Bloomberg Justin Fox does it and comes up with some observations:
These fatality rates can change a lot depending on time and place and access to treatment. The Covid-19 rate is obviously a moving target, so I’ve included both the 3.4% worldwide mortality rate reported this week by the World Health Organization and the 1% estimate from a study released Feb. 10 by the MRC Centre for Global Infectious Disease Analysis at Imperial College London that factored in probable unreported cases. The authors of that study also said that, given the information available at the time, they were 95% confident the correct fatality rate was somewhere between 0.5% and 4%. Gates used the 1% estimate in his article, and when I ran it by Caroline Buckee, an actual professional epidemiologist who is a professor at Harvard’s T.H. Chan School of Public Health, she termed it “reasonable.â€
In a context that includes Ebola and MERS, the Covid-19 death rates are much closer to those of the flu, and it’s understandable why people find the comparison reassuring. Compare Covid-19 with just the flu, though, and it becomes clear how different they are.
The 61,099 flu-related deaths in the U.S. during the severe flu season of 2017-2018 amounted to 0.14% of the estimated 44.8 million cases of influenza-like illness. There were also an estimated flu-related 808,129 hospitalizations, for a rate of 1.8%. Assume a Covid-19 outbreak of similar size in the U.S., multiply the death and hospitalization estimates by five or 10, and you get some really scary numbers: 300,000 to 600,000 deaths, and 4 million to 8 million hospitalizations in a country that has 924,107 staffed hospital beds. Multiply by 40 and, well, forget about it. Also, death rates would go higher if the hospital system is overwhelmed, as happened in the Chinese province of Hubei where Covid-19’s spread began and seems to be happening in Iran now. That’s one reason that slowing the spread is important even if it turns out the disease can’t be stopped.
Could Covid-19 really spread as widely as the flu? If allowed to, sure. The standard metric for infectiousness is what’s called the reproduction number, or R0. It is usually pronounced “R naught,†and the zero after the R should be rendered in subscript, but it’s a simple enough concept. An R0 of one means each person with the disease can be expected to infect one more person. If the number dips below one, the disease will peter out. If it gets much above one, the disease can spread rapidly.
and
The numbers also seem to indicate that Covid-19 is a lot more contagious than the seasonal flu. Average R0 isn’t the whole story, though. Why all the worry about MERS, for example, which with an R0 below one shouldn’t spread at all? Well, it’s extremely deadly, its R0 can rise above one in certain environments, among them hospitals, and … you can catch it from your camel.
There are also some very nice graphs in the article if you’re interested in graphs.
Let’s make a few guesses and play with some numbers. About a third of our entire species caught Spanish flu back in 1918 so let’s use that number as a WAG. Roughly a third of 7 billion people with a mortality rate between .1% and 3% gives us between 2 million and 70 million deaths.
Since I’m over 70 I can’t take the claims that only old people are dying with the nonchalance or even outright glee that some are. Considering the U. S. alone, the numbers above suggest a number of hospitalizations and deaths that are quite likely to overwhelm our health care system and legal system and might even overwhelm our economic system.
I’m also skeptical about those claims. Italy’s population pyramid might explain its higher death rate from COVID-19 but the reports from Iran and China don’t seem to comport with their population pyramids. And then there’s the question of just how much trust we can place in the reports that China is making? There have been claims emanating from Chinese sources that the outbreak in China has been much worse than the Chinese authorities have claimed and that they’re flat out lying that it’s under control. I’ll allow that those claims may be from interested parties but IMO the reality is that we just don’t know.
From what I’ve seen, the only conclusions we can draw right now are directional. Precision is still wanting.
1. The mortality rate increases significantly in ones 60s. Dramatically in the 70s.
2. Underlying disease, probably lung disease, immunosuppressive complications of disease and heart failure, increase the risk.
3. Pneumonia vaccine may be indicated. But hurry up.
4. An overwhelmed system will increase the mortality rate for those locked out.
Other than that Mrs Lincoln………
Thanks for mentioning point #4. I had intended to work that into the post but neglected to.
We dont know enough yet. Trying to extrapolate from countries with younger populations, but much worse medical services probably isn’t helpful. We dont know yet if people re-infect or recrudesce or neither. Older people and sick people as Drew points out seem vulnerable. On the plus side kids seem to do OK.
I will say that unless COvid-19 is much more infectious than the flu I dont see us having as many cases as we did with eh Spanish flu. Crowding and malnutrition were much more common back then. We live further apart in smaller family groups. We have some specific populations that could be very vulnerable, like the immunosuppressed (think transplants) that we didnt have back then, but these are actually fairly small groups.
Finally, it is not just the total number of beds, but the general lack of training for serious communicable infectious diseases that will trouble hospitals.
Steve
Latest estimates i have seen on death rates. Hard to balance out missed asymptomatic cases vs patients currently infected who have not died yet. They, researchers out of Bern, think rates are even worse for older people than we currently think.
https://www.medrxiv.org/content/10.1101/2020.03.04.20031104v1.full.pdf
Steve
Thank you. That’s why my wife is concerned about my traveling for work. Although my employer has asked employees to suspend international travel for work, we are still traveling within the U. S. as usual.
According to the info in the Bloomberg article, it’s estimated to be about twice as contagious as the seasonal flu.
As we can see, incomplete, mis and dis information is still the rule of the day. It should not be surprising. Steve’s comment is the first ive seen that people cannot be reinfected. That would be a huge plus.
One can only do so much. But I wouldn’t attend a conference in Seattle right now.
” Steve’s comment is the first ive seen that people cannot be reinfected. ”
The number of cases where have seen this supposedly happen are tiny and not especially well documented according to my ID people. Just not enough to draw conclusions. We may ultimately find out it can re-infect, but it is too early to claim that. I don’t quite trust info coming out of China. If we get reliable reports out of Italy, then we can worry.
Speaking of Italy, the reports coming out are pretty incredible. Flu expresses itself as a continuum. Some people have very mild symptoms, some a little worse, some a little worse yet and so on all the way up to severe illness that requires ICU care and people die. With coronavirus, with what it sounds like are fewer infections than they would see in a flu season, their hospitals are overwhelmed. They are converting hospital wards, recovery rooms and Ors to ICU beds. Heaven knows how they are staffing the places. More than a few hours in one of those protective suits and you are exhausted and dehydrated.
Steve
China’s median age is 38.4. The US median age is 38.2.
Looking at China’s population pyramid — https://www.populationpyramid.net/china/2020/ , there is a significant 50+ population (as many 65-69 as 0-4).
Iran’s median age is 32. India’s median age is 26.8, Pakistan is 22.8. Nigeria 18.1
There is significant travel between China and Pakistan, China and Africa, India and China/Europe — and less advanced medical systems. Yet India / Pakistan / African countries avoided an outbreak while Italy, South Korea, Japan, US could not?
The other thing in perspective is that in Hubei — the health care system did collapse, but the total number of deaths for all China is around 3000 (likely an underestimate, but not in the tens of thousands). And the outbreak is almost over in China from current reports (and I believe it).
That is a worse case scenario — unless we project that the health care system collapses in Europe / US AND there will not be drastic effective actions in response.
My worry is the US waits until they have an Italy sized situation requiring an Italy sized response.
or India, Pakistan, and African countries are all having outbreaks but they’re submerged in graver health problems like dysentery, cholera, and so on.
I think that’s a foregone conclusion. We always do.
The Coronavirus epidemic gives us a great opportunity to examine the effectiveness of prayer. Along with keeping tab of the sex, age, race, etc., we ought to quiz the sick (and maybe close relatives, too) on the extent of prayer, saying the rosary, and so on, making note on whether the patient ultimately lived or died, in order finally to put to rest all the nonsense talk of “thoughts and prayers” that goes on up even to the President. And if prayer should win out, we can all stop wasting our money on medical research, drugs and treatment and just start praying, which has been shown to work about half the time for football matches.
When ER staff see you visibly praying for the patient, extra effort.
God works in mysterious ways.
Talked with the ICU director of one of the big NYC hospitals today. People are stealing and hoarding the N-95 masks. They are locking them up now. Also, it looks like there have been true failures with these masks (meaning they were applied correctly and still failed). The alternative at most places is a powered unit. Those are not abundant. Also difficult to see through to do fine work.
Steve
That N-95s are failing is an important finding. Thank you.
That provides further evidence for the observation I made some time ago that there is a real opportunity here for additive manufacturing.
The reported failures that I know of are only with intubations, where we place a tube into someone’s trachea. That provides maximum exposure to airway pathogens. I have yet to hear of any failures during normal care of a pt.
Steve
Apologize for the above. Dont want to panic anyone. Will try to be more clear. However, we have solved the whole problem. Being good Eagles fans out here we are going to issue everyone Nelson Agholor jerseys. He cant catch anything!
Steve
Over at Quillette there’s an article implying the low rate of testing and availability of kits may be deliberate CDC tactic to minimize public fears.
Could be.
If you haven’t seen them, pictures from Chinese hospitals with hallways and lobbies standing room only. Staff couldn’t move, let alone treat patients.
Never attribute to malice what can be explained by stupidity.
Or, as Goethe said
” the low rate of testing and availability of kits may be deliberate CDC tactic to minimize public fears.
Could be”
That is really stupid conspiracy theory. No one would do that. Thats the kind of stuff you cant hide.
Query- I cant seem to find anything on sequela after Covid-19. If anyone sees anything please link. Will ask ID folks in morning too. Just wondering if there is long term morbidity, ie is some of the lung damage permanent. It looks like the radiologic changes take a while to go away, but not sure if there are clinical symptoms.
Steve
One other thing which I keep forgetting to mention. While we dont really know the fatality rate for Covid yet, population demographics will make a big difference, it looks like it will probably settle out between 1%-2%. That sounds like a low number to some people, but most people dont have anything to which they can compare this. If it helps when thinking about this, the mortality rate for major surgeries is generally considered to be about 1.5%. Your level of concern about overall Covid mortality should approximate concern over having major surgery. (Of course this just an average and we think we know that age is a large determinant (baseline illness also) but hope this gives a bit of perspective.)
Steve
And that’s 10-20 times the rate for the seasonal flu. Nothing to be sneezed at. So to speak.