Here’s some good news. Covid-19 is significantly less deadly for Ontarians than it was a year ago.
The chart below is an index chart in which daily values are displayed proportionate to their values one year ago today. The value on the vertical axis is the percentagage of the value reported on April 20 last year (for example, if a value is 200 on a given date, that means that the value reported for that data is 200%, or twice, the value reported on April 20, 2020.
(Below black bar = lower than one year ago today; Above black bar = higher than one year ago today)
As you can see, while daily new cases are 7-8 times higher than they were a year ago, and daily new hospitalizations about twice as high, daily new deaths are less than half of what they were last April.
Part of the explanation is our limited testing in spring 2020. It’s possible that if testing levels and criteria were in April 2020 what they are now in April 2021, this chart would look quite different and April 2020 case numbers would have been multiple times higher. Cases are to an extent a function of testing.
Looking at the raw data for cases and deaths, we see that the tremendous growth in cases since last fall has not been accompanied by a proportionate increase in deaths. (Note the pink line in the chart below denoting the number of tests performed each day.)
Looking at the cumulative case fatality rate (CFR) or the total number of deaths to date divided by the total number of cases to date (yellow line in chart below), we see that the fatality rate has been dropping. Much of this is explained by the low volume of testing performed early on (and therefore a lower number of cases), but there is indeed a definite decline in the absolute number of deaths from or with covid-19 reported daily.
Let’s look at the cumulative CFR available for each date so far on which cases or the cumulative CFR itself have peaked:
April 24, 2020: cumulative CFR is 8.8%
May 11, 2020: cumulative CFR peaks at 10.2%
January 8, 2021: cumulative CFR is 2.5%
April 15, 2021: cumulative CFR is 1.9%
These are cumulative values so let’s look at a moving average of the previous 28 days. Here we have the number of deaths reported on a given date divided by the average daily number of cases reported over the preceding 28 days (yellow line in chart below) - this is a very rough approximation of the fatality rate over time.
Again, the low volume of testing, and therfore smaller number of cases, in spring 2020 plays a role. But even since Fall 2020 when testing levels reached high levels, the proportion of cases that ended in death peaked in January 2021 and have been falling since.
The number of daily deaths as a proportion of average daily deaths over the preceding 28 days reached a peak of 2.5% in January (January 4 and again on January 17), but averaged about 1.0% in March and 0.9% in the first seven days of April.
We’ll leave it to others to explain the reasons for these developments, but this is what the official data is able to reveal to us.
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