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COVID-19

A growth rate based projection for COVID deaths

By now you will have heard the White House speak of 100,000 to 240,000 deaths.  I’ve sort of been avoiding looking at the mortality numbers as directly as I do the case numbers.    There are a number of reasons for that, some of them having to do with data, but mostly because it’s emotionally daunting to do so.  It’s one thing to talk about the number of cases that will be reported of an illness with which one has no experience. It’s quite another to look squarely at the number of family members who may ultimately be lost – The number of children who will grow up without a parent or sibling, spouses who will be forever bereft of their mate, or parents whose hearts will alway ache for their lost child.  But I think it’s best to be as frank as we are able about what the future may hold. The future will come anyway, it’s best to be prepared for it.

The projections I have made for deaths to this point have been done by applying a fixed fatality rate to the projection I made for infections.  There are a couple of problems with this approach, and they lead to underestimating the number of deaths. First, the fatality rate has not been fixed, it has been rising.  My last projection was based on a 1.7% fatality rate, now that rate is 2.1%. Second, the infection rate has recently been falling. However, because a patient’s death will lag the onset of symptoms and reporting of the illness.  A very recent paper (https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30243-7/fulltext ) estimates the average time from the onset of symptoms until death to be about 18 days.  So the deaths we are seeing now, are likely mostly from people who became ill in mid March.

Today I’m going to apply the same projection strategy to deaths that I’ve been using for infections.  More precisely I’ve averaged the daily growth in deaths over the last week. It comes to about 27% per day.  I’ll use that percentage, applied to the current number of deaths to project forward for 10 days. Before I do, I want to emphasize that this is not a prediction.  There are many things that could happen to raise or lower these numbers, and I do not have a stand on whether they will happen. This is just what the numbers will look like if the number of deaths continue to grow for the next 10 days at the pace they have for the last week.  I’m starting it off with the 4pm numbers for 3/31 as given by The COVID Tracking Project.

3/31  3,746

4/1    4,752

4/2    6,030

4/3    7,651

4/4    9,708

4/5    12,318

4/6    15,628

4/7    19,829

4/8    25,159

4/9    31,922

4/10  40,502

These are sobering numbers.  It’s easy to see how a curve like this could quickly swell to 100,000 or 240,000 or even higher.

Much has been said over the last couple of months comparing COVID to the flu.  Here is a copy of the CDC estimates for the 2019/2020 flu season.

If this projection holds, COVID-19 will have caused about as many deaths in 2 months as the flu did in 6, and we won’t yet be on the waning side of it or have a vaccine.  We have begun to flatten the curve in the US but only a little. We likely will continue to see increasing growth rate numbers for at least another couple of weeks, perhaps more, and so increasing numbers of deaths for a time after that.  Italy is a couple of weeks ahead of us and is only now starting to see fewer cases added each day.

So be prepared to see some very difficult numbers this month.  The best thing you can do is take care of yourself and your loved ones.  Stay at home as much as you reasonably can. Wash your hands relentlessly each time there is a chance you may have been exposed.  Remember that many of those with COVID have no symptoms, it’s possible you may be contagious without even realizing it.. The more we can reduce transmissions, the less the hospitals will be overwhelmed so the better the prognosis for those who do fall ill.  Our medical professionals are working heroically and at significant personal risk. The best we can do to help them is to minimize the number of patients.

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