How Bad Is the Coronavirus? Let’s Run the Numbers
bloombergquint.com
bloombergquint.com
Does this mean that there's a good chance the death rate is lower than the current calculated 3% with so many recoveries going unreported?
Yes and no. I'm not a doctor so an actual MD will step in here and correct me I'm sure. My understanding from reading both the CDC literature and the WHO literature is that there are two things, the SAR_nCOV2 virus which is out there spreading from host to host, and the COVID19 disease which is one manifestation of the virus in people.
If my understanding is correct, the answer is that not everyone who gets infected by the virus will develop the disease. That can happen for a number of reasons apparently including but not limited to, a small enough sample got your immune system going fast enough that you didn't develop the disease, or you have previously been exposed to something similar enough that your immune system got ahead of the virus, or during the course of the infection your lungs didn't get involved before the immune system had begun producing anti-bodies.
To explain the numbers, the fatality rate is a function of only those people who develop the disease. Your chance of developing the disease is a function of how strong your immune system is and so it develops more commonly in people with weak or otherwise compromised immune systems.
But take this as just one opinion based on reading the literature. It sounds to me as if it is similar to the difference between HIV and AIDS, where you can become infected with the HIV virus but not develop AIDS if that virus is kept minimized with anti-virals.
Here's the WHO drawing a pretty limited distinction, with one name being used for science and one for public communication:
https://www.who.int/emergencies/diseases/novel-coronavirus-2...
"COVID-19 is the disease, SARS-2-CoV is the virus." [1]
1. https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX...
For instance, it says:
Estimates are ~80% of infections non-severe, including asymptomatic infection likely.
The language there doesn't separate the asymptomatic infections from the disease.
Therefore it feels like at this point their data would be pretty representative of what percentage of the cases are severe vs critical and what the death rate is (accounting for both the overwhelmed medical case in Wuhan and for the under control case in rest of China).
South Korea is also doing a pretty good job with testing to control the outbreak although they haven’t yet gotten it as under control as China does. So their numbers would be a good data point to cross-validate the China numbers.
In countries like Italy (or Wuhan early on) the number of confirmed cases wasn’t equal to total cases as evidenced by continued growth of the epidemic. So it’s reasonable in those cases to assume that more severe cases are being found and less severe ones are being missed.
https://twitter.com/MikeIsaac/status/1238604080571772928
I don't see why they would back off of the monitoring and fever clinics without some better measure in place (a vaccine or effective treatment or whatever). It's of course very likely there will be new cases. The likelihood of unchecked spreading seems much lower.
I think there's a decent chance the outcome won't be nearly as bad as the worst case scenario, but the worst case scenario is pretty scary. There is a non-zero probability that this wave is only beginning, that there are going to be future outbreaks and pandemic waves this year, and that by year's end there'll be millions of deaths globally.
Anyone with a fever is screened for the infection using a portable CT scanner (they don't do a full image, they take a couple slices).
People with suspect CT results are tested and held in quarantine until the test result comes in.
The virus simply will not spread as fast in those conditions as it did when local officials were covering up, and people can start moving around more without backing off those conditions.
The, e.g. “32 million cases of flu” reported by the CDC is not based on 32 million positive test results. It’s extrapolated based on a factor of how many cases require hospitalization, and how many people seek medical care, which itself is based on antibody and behavioral surveys.
> The numbers of influenza illnesses were estimated from hospitalizations based on how many illnesses there are for every hospitalization, which was measured previously (5).
> Some people with influenza will seek medical care, while others will not. CDC estimates the number of people who sought medical care for influenza using data from the 2010 Behavioral Risk Factor Surveillance Survey, which asked people whether they did or did not seek medical care for an influenza-like illness in the prior influenza season (6).
After reading more about it [1] you almost wonder how much better than a WAG (“Wild Ass Guess”) it really is.
Frankly I am finding this whole area of medical science entirely underwhelming relative to the potential impact to lives and economies of the world.
The problem is we don't have the same data for this virus yet.
There was also a statistical analysis of the Diamond Princess cases. That produced an estimate that about 17% of infections were asymptomatic. [1] It's possible that there are less asymptomatic cases among the older population, but between the Guangdong and the Diamond Princess data, I doubt it.
The 3.4% CFR that everyone is looking at is also dependent on some reasonably adequate level of medical care. If this thing blows up, most people are going to be on their own, and in the absence of a miracle drug that is widely available (maybe Chloroquine?), the fatality rate with home care I would expect to be something like 10-15%.
[1] https://www.eurosurveillance.org/content/10.2807/1560-7917.E...
That seems unlikely.
Testing capacity in lots of the world is extremely limited. The US is reserving test kits for the most sick/at risk; people at a low risk are unlikely to be tested.
It seems to me that the focus would be on testing alive people, and that we are subsequently undercounting deaths - at least, in these relatively early stages.
But as everybody points out, the correct number can only be claculated after the fact. and even the it might be of.
So long term a lower CFR seems to make sense.
The people who are dying are usually older, or have preexisting conditions and their deaths can easily be chalked to their age/condition.
"Is the death rate 0.5% or 5%？It depends on whether the hospital is overloaded. Let's take a look at the data."
I'm not sure where you're getting the 3% number from. If you read the New York Times maps page data[1] and just divide the total deaths by total cases you get 3.7%, but that isn't the death rate because it doesn't take in to account a lot of factors.
Instead, there's a good article[2] about how bad the virus will get, that says estimates put it in the range of 0.1% to 3%. (With the seasonal flu being somewhere around 0.1%, but the Spanish Flu of 1918 being somewhere around 3%.)
That said, the general intuition that less reporting of cases means that some part of the death rate is over-inflated makes sense. But also consider that there are factors that go in the other direction. Anyone who currently has the virus but has not recovered or died can be under-inflating that rate. And there are likely lots of other factors, which is why articles often mention that the "true" death rate cannot yet be calculated.
(Also the death rate varies a lot with age, and isn't the only factor in determining the "badness" of a virus. Which that second article goes into more depth on—things like how contagious it is, and how early a vaccine can be developed. So the average rate being half of the current numbers doesn't necessarily mean the concern is over-inflated as well.)
[1]: https://www.nytimes.com/interactive/2020/world/coronavirus-m...
[2]: https://www.nytimes.com/interactive/2020/world/asia/china-co...
"Scientists working at the London School of Hygiene and Tropical Medicine, Imperial College London and the Institute for Disease Modeling have used these approaches to estimate the infection fatality rate. Currently, these estimates range from 0.5% to 0.94% indicating that COVID-19 is about 10 to 20 times as deadly as seasonal influenza. Evidence coming in from genomics and large-scale testing of fevers is consistent with these conclusions. The only potentially good news is that the epidemic in Korea may ultimately show a lower CFR than the epidemic in China.
...
"On balance, it is reasonable to guess that COVID-19 will infect as many Americans over the next year as influenza does in a typical winter -- somewhere between 25 million and 115 million. Maybe a bit more if the virus turns out to be more contagious than we thought. Maybe a bit less if we put restrictions in place that minimize our travel and our social and professional contacts.
"The bad news is, of course, that these infection numbers translate to 350,000 to 660,000 people dying in the U.S., with an uncertainty range that goes from 50,000 deaths to 5 million deaths. The good news is that this is not a weather forecast. The size of the epidemic, i.e., the total number of infections, is something we can reduce if we decrease our contact patterns and improve our hygiene. If the total number of infections decreases, the total number of deaths will also decrease."
[1] - https://www.marketwatch.com/story/why-this-epidemiologist-is...
https://medium.com/@tomaspueyo/coronavirus-act-today-or-peop...
I dumped this into Tableau, graphed it and put an exponential trend line over the top. The UK and US data dropped almost perfectly onto an exponential (R-squared > 0.99 for both, P value better than 0.0001 for both, whatever those mean). The visual fit was remarkably good.
The italian data very obviously did not fit so well. It clearly was flatter than the best fit exponential (strange, given that covid is totally ablaze there) and it had an R-squared of 0.946, though it's P value was still less than 0.0001.
Can anyone comment? The raw data for italy is below.
date,cases
2020-02-21,20
2020-02-22,79
2020-02-23,150
2020-02-24,227
2020-02-25,320
2020-02-26,445
2020-02-27,650
2020-02-28,888
2020-02-29,1128
2020-03-01,1694
2020-03-02,2036
2020-03-03,2502
2020-03-04,3089
2020-03-05,3858
2020-03-06,4636
2020-03-07,5883
2020-03-08,7375
2020-03-09,9172
2020-03-10,10149
2020-03-11,12462
2020-03-12,15113
2020-03-13,17660
2020-03-14,21157
date,cases
2020-02-26,15
2020-02-27,15
2020-02-28,19
2020-02-29,24
2020-03-01,42
2020-03-02,57
2020-03-03,85
2020-03-04,111
2020-03-05,175
2020-03-06,252
2020-03-07,352
2020-03-08,495
2020-03-09,643
2020-03-10,911
2020-03-11,1182
2020-03-12,1577
2020-03-13,2184
2020-03-14,2628In any case the data is surely of confirmed cases, so these have got past the testing, no? And I'm not sure if that would produce a flatter-than-exponential curve, which seems to be what it is.
And then for the US, if most places are doing a high percentage of the needed tests, then the test results should reflect the real growth. Given the limitations on testing, we likely won't have a good understanding of this for weeks to come (people on the internet saying they should have been tested is only worth so much).
A total layman on the subject matter. Stop writing about corona if you’re not an expert. Stop reading and sharing non-expert opinions.
This article leaves off about where a similar report on epidemiological models did a couple of weeks ago: Covid-19 will be very very hard to control if persons showing no symptoms spread the disease too often, but we do not know whether or not they do.
The naive or “known” CFR is the fatality rate to-date divided by the number of positive tests to date.
For example, China at one point decided to consider a large number of people as positive cases based on purely clinical symptoms because they didn’t have the test capacity or specificity to definitively diagnose them. Which is why their case count gapped up one day.
The CFR after all cases have concluded is an upper bound on the IFR. There seems to be no true consensus on the percentage of asymptomatic or very mild cases which would not seek treatment or even testing. This number (which is basically unknowable during an outbreak) is a multiplier on the case count, and acts to reduce the true IFR.
Lastly, as we’ve seen quite clearly... How bad it is depends almost entirely upon the person, or at a higher level, the demographics of the people who are infected.
Italy as of March 11;
> Of the patients who died, 42·2% were aged 80–89 years, 32·4% were aged 70–79 years, 8·4% were aged 60–69 years, and 2·8% were aged 50–59 years (those aged >90 years made up 14·1%). The male to female ratio is 80% to 20% with an older median age for women (83·4 years for women vs 79·9 years for men).
Likewise, the outbreak in a WA nursing home was devastating to an elderly population where they would see 5-10 patients die in an average month.
IMO the path forward is either successful containment—which seems extremely unlikely given the transmission characteristics, but apparently China was able to do it? But where you constantly have to be watching for pockets of reemergence and clamp them down.
Or, if we can keep the virus away from high-risk populations while it spreads “like a flu” through the majority of the population, then you will see herd immunity kick in which ultimately works like a vaccinated population to prevent further outbreak and protect the at-risk population from ever becoming infected.
[1] - https://www.thelancet.com/journals/lancet/article/PIIS0140-6...
There are other important factors to consider.
There will be a percentage of infected individuals who otherwise would have survived had they had access to respiratory assistance by trained medical staff at a hospital.
But as medical staff get overwhelmed, get sick, or die, as free room in Intensive Care Units is used up, as respiratory assistance technology becomes unavailable because it's busy supporting other patients, the death rate will rise beyond what looking at the demographic data alone might lead one to believe.
In addition, there are likely to be extra deaths from other, completely unrelated diseases and conditions for which people can no longer get treatment as hospitals and medical staff get overwhelmed, and as we run in to medicine and medical equipment shortages from lack of supply in China (and, I expect before long, from India and other countries on which the US medical system relies).
To make matters worse, the people sick with COVID-19 will likely infect a lot of vulnerable patients in the hospitals they go to, as most hospitals just simply aren't equipped to effectively contain such infections, especially when there are so many of them. This will increase the death toll even further.
There are many group living facilities such as prisons and nursing homes which will likely be affected by this as well. They will be especially vulnerable because the people there tend to already not be in the healthiest shape and have weakened immune systems.
They separated Native American and immigrant families in the recent past, why stop now
I'm all stocked up on TP. And also boxed wine. So I'm good to go.
Toilet paper shortages are the least of our problems, hospital capacity to treat severe and critical cases is the issue at the moment.
Will await a mirror.