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In a rare piece of good news about Covid-19, a team of infectious disease experts calculates that the fatality rate in people who have symptoms of the disease caused by the new coronavirus is about 1.4%. Although that estimate applies specifically to Wuhan, the Chinese city where the outbreak began, and is based on data from there, it offers a guide to the rest of the world, where many countries might see even lower death rates.

The new figure is significantly below earlier estimates of 2% or 3% and well below the death rate for China based on simply dividing deaths by cases, which yields almost 4%. While it is still higher than the average 0.1% death rate from seasonal flu, it raises hopes that the worst consequence of the coronavirus will be uncommon.

Cutting against that optimism is the expectation that, because no one was immune to the new virus, “the majority of the population will be infected” absent the quick arrival of a vaccine or drastic public health interventions such as closing public places and canceling public events, the scientists conclude in a paper submitted to a journal but not yet peer-reviewed.

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The expectation that a “majority” of a population will become infected reflects a worst-case scenario about who encounters whom, something modelers call “homogeneous mixing.” But even the more realistic assumption that not everyone mixes with everyone else means that “at least a quarter to a half of the population will very likely become infected” absent social distancing measures or a vaccine, conclude Joseph Wu and Kathy Leung of the University of Hong Kong, leaders in the modeling of infectious diseases, and their colleagues.

The Covid-19 pandemic is sparking efforts to calculate how deadly this new disease is. One measure is called a case fatality rate. While the formula is simple, it’s difficult to get a precise answer.

The better news involves fatality rates. To calculate those, the researchers used data from Wuhan, especially the age distribution of 425 early cases and 41 early fatalities there.

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The chance of someone with symptomatic Covid-19 dying varied by age, confirming other studies. For those aged 15 to 44, the fatality rate was 0.5%, though it might have been as low as 0.1% or as high as 1.3%. For people 45 to 64, the fatality rate was also 0.5%, with a possible low of 0.2% and a possible high of 1.1%. For those over 64, it was 2.7%, with a low and high estimate of 1.5% and 4.7%.

The chance of serious illness from coronavirus infection in younger people was so low, the scientists estimate a fatality rate of zero.

As physicians and researchers have seen since the start of the outbreak, many infected people never become sick. As few as 14% of people in Wuhan with early coronavirus infections were being detected, said epidemiologist Jeffrey Shaman of the Mailman School of Public Health at Columbia University, who led a study published on Monday in Science on undocumented coronavirus infections.

“I think there are many more than the [nearly] 70,000” confirmed Covid-19 cases in Hubei province, Shaman told reporters.

That means the “infection fatality rate” — deaths among people who have the virus but might or might not show disease symptoms — is even lower than Wu and his colleagues calculate.

Despite Wuhan’s heroic efforts to treat patients, the suddenness of the epidemic overwhelmed hospitals there, much as it has in northern Italy. In countries that got more advance warning and prepared better, especially if social distancing succeeds in “flattening the curve” enough to dampen what would otherwise be a tidal wave of Covid-19 cases, the death rate is likely to be lower still.

“Fatality risk estimates may not generalize to those outside of [Wuhan], especially during subsequent phases of the epidemic,” Wu and his colleagues write. “The increasing availability of newer, and potentially better, treatment modalities to more patients would presumably lead to fewer deaths.” That’s true even within China, they find: “To date, the death-to-case ratio in Wuhan has been consistently much higher than that among all the other mainland Chinese cities.”

Lest anyone be tempted to downplay the threat, the scientists caution that Covid-19 is on track to infect millions of people. If social distancing fails to dampen the number of cases at any one time, overwhelming health care systems, the death rate would be higher.

  • The small sovereign state of San Marino is completely surrounded by Northern Italy. It has seven times as many reported cases on a case per million basis as Italy. This suggests that incidence levels in Italy are far higher than cases reported, and reduces ridiculous estimates of death rate made on the basis of reported cases.
    So-called cases come from testing. No test = no case. No-one has any idea of the true number of those infected. Some educated guesswork concludes that unreported illness is seven times greater than established cases.
    Fatalities are absolute. It’s hard to get solid info on the ages of fatalities, but the 71st person to die in the U.K. was the first fatality under the age of 50. This indicates that dubious WHO information may be right when it reports that fifty per cent of fatalities have been in the 80+ age group.
    Current growth in fatalities is following a similar curve to that of growth in cases. Both indicate that spread in countries without restrictions is doubling every four days.
    The most important test needed, if you think of it, is the test to find whether you’ve had it. If you’re so sick you need to be tested in hospital, it doesn’t matter that much what you’ve got. If it is widespread and largely undetected, then the problem is perhaps less serious than many fear. That’s the reason they seek to contain the spread so that these things can be worked out and so that whatever measures that can be provided are in place.
    Also remember incubation times. The number sick has doubled or quadrupled before the afflicted person shows the symptoms, depending on whether the incubation is four days or eight days in duration.

    • I very much agree with you that the most important test is the one that tells you if you have had it. I’d also like to know if having a mild form gives you immunity. I don’t understand why I don’t hear the experts talking about the Diamond Princess more. As tragic as that was, you have to believe that everyone on that ship was exposed to the virus given the recirculated air, long incubation times of the virus and the high R0 factor of the virus. Understanding how many people got infected, critically sick or died would tell us a lot about what we’re up against.

    • Steve, Slate.com had a pretty nice analysis of the Diamond Princess experience as a floating Petri dish.

      Rather than extensive quoting, I’ll just give you the link: http://bit.ly/3bbhfrk

      Not to go tinfoil hat on you, but the reason you don’t hear the experts talking about the Diamond Princess’ experience may be because it doesn’t fit their narrative or serve their purposes. How many clicks or eyeballs can they continue to rack up if they say, “Y’know what? The cruise ship pretty much validates this a nothing more than a flu, a little tougher on the elderly but a lot less dangerous to the young.”?

      Can’t feed a panic with that report.

  • With all due respect, flattening the curve doesn’t take human nature into account. How long do you really think seniors will stay in and how many more will actually get it in the long run because they have been duped so many times before they will think the danger is passed. Those with immune problems stay in during flu season, but for six months? I don’t think so. Even the biggest germaphobes I know can’t last that long.

    And why are they still encouraging fast food, take out, not mentioning gloves, not mentioning nutrition and vitamins, and not mentioning washing the cans containers you just brought home from the store. Common sense measures for many seniors every day!

  • @panicdemic
    I agree you can’t always trust the numbers coming out of China. But as far as I can see China is under playing the seriousness of the illness and the number of deaths. I can’t see a reason why they would inflate the effect of the illness on the young, while not accurately reporting the number of deaths in the overall population. Unless this is supposed to be some kind of a weird reverse psychology on their part, I think we better be worried. On the other hand, we should also all be happy we’re aIive to be worried. So let’s all try to have the best day we can, the best week we can, and the best lives we can – without hurting other people with irresponsible behavior.

  • okay if you are going to mention the start then each country should have its on set of statistics and the age groups, because it is said that younger people should its zero and then millions of people are affected. the percentages do not make sense to what is in the article

  • Are you lying with statistics?

    Why aren’t you using US statistics? I know. Because they are a lot lower.

    Wuhan statistics are based on a country where there is not that much concern about the health of a population that also includes slavery and millions of people working at very low wages with limited healthcare

    • I am not sure who you are referring to, but statistics for death rates in the US would not be reliable. We do now know how many people have been infected and have now recovered because we have so little testing. So, public health people are hoping it’s a very large number so the death rate is low, but we do not know. Also, we are in the beginning of the epidemic -the numbers are growing way too fast to claim a stable figure. US statistics would be the worst ones to use at this point.

    • And US is a country which is working overtime to monopolize any potential treatments, so it can profit from them.
      So when other countries are trying to find a cure, US is just looking at opportunities to make money out of this pandemic.

      They are trying to bribe a German pharmaceutical company for exclusive rights for an experimental vaccine.
      And also trying to monopolize Gilead Sciences vaccine so that other countries can’t get a patent.

      They have not listened to calls from other countries to temporarily lift sanctions on countries like Iran and Venezuela.

      In times of crisis, capitalist countries like US show their true colours.

    • China says the virus has stopped affecting people there..Do you believe that ..I dont..but I am doing what the state says and stay i..I dont want to affect others or my family or myself..it makes sense to do what they say ..but when we pick up drive thru wear gloves..wash your hands when you get home..and only go out when we need to..God Bless those who are already sick..Bless the Doctors all the time health care workers..and I pray Our God will protect all those who are hurting tonite because of lost wages..we are Americains and we are going to band together to help each other..God Bless each and everyone..Stay in Stay safe..take care of your babies..and REMEMBER WASH YOUR HANDS..STAY SAFE..

    • If Iran gave up its nuclear ambitions, the sanctions would be lifted immediately. I do not support those who are AntiAmerican. They are my true enemies.

      But what went on with that German Company is of interest. But it seems there is much cooperation going on in the World but pharma companies paying salaries need to have a way to generate income to cover those salaries.

      Vaccines are very risky business as many times the need is over before the vaccine is ready. So government subsidization of vaccines may be justified. But there are probably close to 100 efforts around the world to develop such a vaccine. It will be very confusing.

    • Annie Well – the US is trying to get control of a possible vaccine – but that does not necessarily mean we are going to rip of the rest of the world and gouge them – I do not know if you know about biotech but there is a lot of it- it is not reasonable for anyone to think they can “monopolize” it – sure, the first maker of an accepted vaccine can make a heck of a lot of money – but there is every good reason to expect many vaccines will come to availability at once. IF we fund all the companies which are in the game fully, and clear all red tape – and all the world does likewise -and national governments temporarily suspect enforcement of copyright/patent laws – then we will likely have a lot of vaccines available in a few months – some will duplicate others – fine – just get them to the people. I do not think many people think they can monopolize this.

  • Hi, sharon very intresting read in deed thank you.
    I’m however not convinced of the following possible transmission of air induction from mechanical air ventilation.

    Whilst social distancing to curve the impending virus COV-19
    I’m interestingly minded science seams to out rule the following, why is beyound me.
    Interestingly we use all modes of transport ie with air ventilation, in fact every conceivable commercial property and domestic home almodt has a ventilation system.

    My concerns may be viewed with caution, is it possible that we can be in some way exposed through air ventilation.
    Whilst there are ongoing studies and scientific analyses ongoing to understand transmission,,im convinced recycled air has a hidden agenda, duct systems harbour the worst bacteria k own to man from there inlet to filteration and thus exspelked back out through a recycling process, whilst a vast array of filteration on plains trains ships may have adequet filteration systems I’m not so convinced they cut the chase,
    Further that of other module of transport ie rail networks,vehicles, etc, we thrn kind of step into the twilight zone, are commercial property’s or domestic home filterations adequet, are there possibilitys of transmission from re-circulated air, are filters up to speed in preventing transmission,
    Asxwe sneeze cough tbis is quite right sprayed out in billions of droplet forms, just like some one throwing a bag of flower into the air in a crowed of say 500 people the result we all get contaminated the point in many global comercial and domestic settings such transmission is drawn in from circulated air exspelked back out as clean air such that its possible yet cannot be ruked out of mode of transmission.
    Filters and ductings in testing would confirm inward outward contamination and thus contamination would be found on sample swabbing of acute areas through inlet outket and of course the circulated filter area.

    Just a point of mentioning something that has possibly been overlooked.

  • Not sure why I keep hearing about how superior Italy is to the US when dealing with this outbreak. Their mortality rate for this virus is roughly 4 times that of ours. God bless Italy but lets stop pissing on the US out of habit. Put the political stuff behind us and come together with positivity and proactiveness.

    • True mortality rate is not calculated by dividing deaths by total cases, as those cases have yet to resolve. Mortality rate is calculated by dividing total deaths by the sum of total deaths plus recoveries. Right now the mortality rate in Italy on 3/18 is 42.52% ….. 2978 deaths divided by 2978 plus 4025 recoveries. In the USA it is still early, but the mortality rate is actually 54%

      What these numbers do not take into consideration is the number of unreported infections that recovered on their own and were never tested. They would count towards the true mortality rate. There is no way of knowing the true number without testing everyone for antibodies to see exactly who caught it. Anyway, the number of actual deaths in Italy is staggering when compared to their overall population of 50 million. I believe this is due to inadequate hospital facilities being over run with too many patients who need a ventilator to survive and/or recover.

  • Paige – Those numbers are from China. I don’t believe anything from that nation right now. I do believe in Italy’s numbers and US. No deaths in the young so far. Yes it can cause serious sickness, so can a plethora of other diseases. I do hear from time to time death of the young. Like the 21 year old soccer coach who also had pneumonia and was battling Leukemia.

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