Thread by @MoriartyLab

Quebec COVID-19 hospitalization data to Dec 23

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First: Why all Canadians should be following QC:

🔵QC (and Nova Scotia) currently doing 2X more per capita testing than any other province
🔵QC reports severe COVID outcomes MUCH faster and more completely than other provinces

Key take home message: What is happening in Quebec is almost certainly happening in other provinces.

Outside QC we just know less because reporting is slow and/or less complete.

Per cap cases likely similar in QC, other provinces except *maybe* NL, PEI

https://twitter.com/MoriartyLab/status/1474456748576714756?s=20

Quebec hospitalization data to Dec 23, from @INSPQ.

Reporting from Dec 24 on slow/incomplete, so only going to Dec 23.

All links to source data here, in case you doubt numbers I'll show in next tweets.

inspq.qc.ca/covid-19/donne…

inspq.qc.ca/covid-19/donne…

inspq.qc.ca/covid-19/donne…

@INSPQ Here are the 7 day averages for cases, hospitalizations, deaths reported in Quebec up to Dec 23

Note upturn in hospitalizations BEFORE cases. The big increase in cases likely started earlier than we knew from testing numbers.

Note that deaths still flat.

Why? See next tweet.

@INSPQ People are hospitalized with COVID about 1 wk after symptom onset. Assuming people are tested as soon as they show symptoms, we should see hospitalizations rise ~1 week after cases.

Deaths should rise 4 weeks after cases.

This graph shows expected 1, 4 week lags for hosp, death

@INSPQ Now, let's estimate the hospitalization rate on Dec 16, using new hospitalization numbers from Dec 23 and cases from Dec 16.

It's 2.0% (75 new hosp/3666 new cases).

Do we expect this? No. It's unexpectedly high.

What should the hospitalization rate be, roughly?

@INSPQ The OECD hospitalization rate for people younger than 40 is about 0.4%

This is for Alpha strain, so "milder" than Delta-- and probably somewhat milder than Omicron.

The OECD hospitalization rate for people 40 and older is about 12%. Again, Alpha.

@INSPQ BTW, reported Cdn mortality, hospitalization rates have consistently been higher than OECD avgs throughout epidemic. We under-detect milder cases.

OK. How many of Quebec's cases in the 4th wave (Jul 18-present) have been people under 40?

67%

How many under 40 last 14 days: 66%

@INSPQ Let me calculate the expected hospitalization rate for all QC cases in 4th wave, based on number of cases in each age group.

Haven't actually done this yet, so please be patient while I calculate.

Actually, it's simplest to do this with the Dec 16 case data, to keep the comparison as simple as possible.

Based on the OECD age-specific hospitalization rates for unvaccinated people and ages of cases reported Dec 16 we'd expect a hospitalization rate of 4.3% by Dec 23.

Assuming 90% protection against severe outcomes provided by vaccines and 78% of QC population fully vaccinated AND that cases on Dec 16 reflect that we'd expect a hospitalization rate of 1.3%.

But if unvaccinated people accounted for 60% of cases (Omicron), we'd get a hospitalization rate of about 2%.

So, the % of Dec 16 cases hospitalized by Dec 23 is pretty much exactly what we'd expect.

At 2% hospitalized (for younger cohort) that's 200 new hospitalizations/10,000 new cases coming soon across the country. This will increase as cases spread to older people, although higher vax rates will help a little.

Do the math

How many new Cdn cases REPORTED from Dec 16 to present?

At min 2% hospitalized that's 3,336 new hospitalizations from REPORTED cases contracted from Dec 16-23.

These are estimates--it will likely be higher.

We have almost no reporting or action anywhere right now

For those who may not have been able to see text on the png files I posted earlier in this thread, here is graph 1 (NOT lagged), in jpeg format.

Here is graph 2, in jpeg format (lag-adjusted)

Finally, if Omicron is similar in severity to Alpha, here are estimates of expected future deaths, hospitalizations and ICU admissions in Canada.

225,000 hospitalizations
61,000 ICU admissions
56,000 deaths

https://twitter.com/MoriartyLab/status/1475231738720927753?s=20

It's too soon to know if ICU, death rates will be similar, but we should in next 2-4 weeks.

Problem is: that's too late to act, with current exponential spread. We could see infection of all susceptible people in Canada by end of January at reproduction rate pre-Christmas.

I'm working now on estimates of expected and actual hospitalizations, ICU admissions, deaths in different Canadian regions to help people see how much under-detection/under-reporting of severe outcomes happens outside Quebec.