Ed Tubb Profile picture
2 Nov, 8 tweets, 2 min read
1/n Not long after I did the attached chart of cases by age, I realized I could use the Ontario database to predict how deadly each day's set of new cases might be, based on the age breakdown and their average death rates.

That's easy enough.
2/n First, we know two important things about the COVID-19 death rate.

1. It's become a lot lower over time, probably because we're better prepared to treat it.

2. It takes some time for some patients to die.
3/n If you're looking to estimate how likely any given patient is to die, it's simple enough to resolve those issues.

1. Throw out data from the spring.

2. Throw out recently infected cases, and any case listed "not resolved".
4/n Another important thing to note is that some folks are especially vulnerable to COVID-19, people in nursing homes, especially.

Thankfully, the Ontario database tells you if someone caught the virus in an outbreak — and that's a pretty good proxy for those nursing home cases.
5/n So: We have a method.

Take the age distribution and outbreak status of each day's cases, and run that against the average chance of death for similar cases reported June thru end-Sept.

For Ontario, that looks like this:
6/n Clearly, 1. age is the primary factor in whether any given patient dies, and 2. Ontario's was much better at treating the average patient over the summer than in the spring.

OK. Now it's just a matter of taking each day's set of cases, and using these averages.
7/n And here you have it, Ontario's COVID-19 pandemic by a single metric of "expected deaths."

Basically, based on the age and outbreak status of the folks who got sick in Ontario today, this is the number you'd expect to die, based on the rates we saw over the summer.
8/n The *other* thing you achieve by normalizing to the averages over the summer is you now have the ability to directly compare wave 1 with wave 2.

(Add this to my endless list of tweets on why deaths aren't yet spiking in Ontario's fall wave).

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More from @EdTubb

2 Nov
1/2 Here's this "expected deaths" curve overlayed with the province's cases by day, left, and the observed deaths tally, right.

The "expected" curve peaks on April 17 (when nursing home outbreaks peaked by cases).

The real curve peaks May 4.
2/2 You see what looks like a similar match with a peak on the downside of the "expected" curve at May 14-15 with one on the real curve around May 27.

So... ballpark: If it's predictive, this "expected deaths" number could be a look ahead by 10 to 14 days.
Testing this:

On Oct. 1 "expected deaths" hit a 7-day avg. of 5.5 deaths a day; we passed that 15 days later (on Oct. 16.)

On Oct. 16 "expected deaths" was at a 7-day avg. of 8.0; we passed that 17 days later (today.)

That's pretty good — maybe a bit longer than the spring?
Read 4 tweets
15 Oct
1/n I've been talking for a bit about uncertainty with the Ontario COVID-19 data over the new testing system.

Here's a chart that illustrates my caution: This is cases by the day a patient's sample was collected:

A steep slope up to a peak on Sept. 29.

Then a *big* dip.
2/n That dip itself is very easy to explain:

Dark blue is the day appointments started.

Light blue are the days some centres were closed to prepare. Before that, there were a few days of extremely long wait times.

It's what's happened *after* the dip that I'm not clear on.
3/n My question: Is the new testing regime equally as good at catching cases as it was in late Sept.?

If it is, then the data is evidence cases have actually been falling since hitting a peak in late Sept. — maybe they *have* plateaued.

The signal would be something like this:
Read 5 tweets
15 Oct
Ontario is reporting 783 new cases this morning, with 5 deaths.

39,961 completed tests, which is up.

Looks like sample-taking is rebounding, too: 49,717 samples added to the queue yesterday.

(That's why "under investigation" is up nearly 10k to 36k)

data.ontario.ca/dataset/status…
The labs first need to *have* samples to be able to test them, so the fact more tests were collected than tested yesterday does not yet suggest there's a "backlog" problem.

With big input numbers, it's normal for a large total of tests to be in the queue at the end of the day.
The question is whether the labs can handle this input after it comes in, so should watch to see if the completed number gets back up into the mid-to-high 40k range tomorrow.
Read 4 tweets
14 Oct
1/n Here's a short thread on COVID-19 deaths in Ontario's second wave.

Why are deaths still relatively low?

After all, weren't we seeing far more people dying in Ontario at this time in the spring?

Well, yes... and maybe no. Image
2/n Here's the fall 2nd wave so far, left, compared to the spring 1st wave to its peak by daily cases, which came in mid-April.

As you can see: In the spring, deaths followed soon after cases — we clearly have *not* seen a similar pattern so far in the fall. ImageImage
3/n But let's remember the spring:

Infections were coming hard and fast.

The system was not prepared.

We weren't testing.

As a result. That case curve *was itself* delayed.

ie: Many infections happened weeks before the case was confirmed; that largely doesn't happen now.
Read 9 tweets
24 Sep
As of 8 pm Wed., Ontario's regional public health units are reporting another 373 confirmed or probable COVID-19 cases, with 4 more deaths.

The 7-day avg. is 🔺 to 403 cases/day and 🔺 to 1.7 deaths/day.

First time the 7-day avg. has been north of 400 cases/day since May 26. Image
Accounting notes:

- Toronto reported 129 new cases but the unit's total rose by 99. In the past, this would suggest data cleaning scrubbed 30 cases, but I don't know yet if that's the case today. Regardless, my total for the day includes 129 from Toronto.
- The province's total for Toronto from the same reporting period was 102.

- The province also had 0 in Middlesex-London, but the unit reported 12.

- So: Add 30ish from Toronto and 12 from London to province's 335 from this morning, and it's much closer to what I'm seeing.
Read 7 tweets
22 Sep
As of 5 pm Tues., Ontario's regional public health units are reporting 50,055 confirmed or probable COVID-19 cases, with 2,872 deaths.

The 7-day avg. is 🔺 to 393 cases/day and slightly 🔽 to 1.4 deaths/day.

470 cases today by my count.

7-day avg. is doubling every 9-10 days.
After a while, you kinda run out of ways to say "this looks bad," but it really is on pace to get awful.

No matter how many more cases we're finding now vs. the spring, Ontario can't sustain this pace of infection for long — and if it does, these rates get ugly quick.
... and then hospitalizations and deaths will follow.

Meantime: Compare where Ontario's larger health units are at now (left) vs. the start of August (right):

From falling cases to frightening growth rates.

It's a hell of a turnaround in less than two months.
Read 4 tweets

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