NEW: our big story as trailed on Friday is a detailed analysis of the critical importance of vaccination in beating Covid

Top-line: if US had matched vaccination coverage of leading European countries, it would have *halved* its Covid hospitalisations…
This is due to the very steep age-gradient in risk of severe Covid, meaning even small gaps in coverage among the most elderly carry huge risk
Here’s vax uptake and waning among the elderly in the US and several European countries.

Note how that red "unvaxxed elderly" segment extends much further right for the US, with millions still vulnerable well into its summer Delta wave.

Far more severely waned second doses, too
And this is after the US got off to a big head-start, getting second doses into elderly arms well ahead of Europe.

(👀 second row of charts here)

But where the black line rose first, it stopped rising at a much lower level than leading European countries.
So what we’ve done in this story is combine all the data we have on age-specific exposure:
• Baseline pre-vaccine risk of severe disease by age
• Share of age group with x doses, and how much waning
• Vaccine efficacy against Delta and Omicron
• For every day of the last year
The result: population-weighted scores for exposure to hospitalisation over time
• Eng & US started rollouts earlier
• But soon overtaken by EU countries (US because rollout slowed, England because AZ)
• Boosters pushed exposure yet lower
• Omi’s immune evasion caused a bump
And that’s where we get these charts showing how one country’s hospitalisation toll might have looked if it had another country’s vax coverage.

We start with the observed data, here for the US, and then multiply it by the ratio between US and Danish exposure scores every day
We can also flip the comparison around and see, for example, how English Covid hospitalisations would have looked if we had US vaccination coverage.

The answer: much worse, coming quite close to last winter’s peak.
Another interesting counterfactual, as also calculated by @PaulMainwood last week for the Omicron period, is what would things look like without boosters?

In England, hospital occupancy would have (un)comfortably exceeded last winter’s peak.
And here’s England with Polish rates of vaccination 😬
There’s an extensive methodology box on our story, and full reproducible code on GitHub…
So, why does all of this matter?

Because of this chart.

Covid’s IFR in England has fallen steeply since last winter, but that wasn’t by chance, it was [largely] because of vaccines.

In countries with poor vax coverage, Covid will still be far more than twice as lethal as flu.
For example, here are CFRs for England, Portugal and the US (IFRs are only possible for England, thanks to the @ONS infection survey 🙏)

Just like in hospital exposure chart, poor US vax coverage means its CFR has stayed much higher until Omicron, and remains higher with Omicron
And while Omicron’s intrinsic mildness is good news for us all, invaluable data from France (via @nicolasberrod) shows that vaccines still do more to reduce Covid’s lethality than Omicron does.
This matches what we’re hearing more hospital doctors all over the world: even with Omicron, unvaccinated people remain at substantial risk of severe disease and worse
So as long as large numbers of elderly people remain unvaxxed or have waned protection, Covid will continue to be a major burden.

If we want Covid to be over, and to be able to get on with our lives, we need to get everyone vaccinated.
And as many have said, we must also remember Covid is much more transmissible than flu, so even though its lethality per-infection has fallen, the number of infections in any given year is still far, far higher.

Down to 2x lethality 👍
5x infections 😬
It’s also worth noting that Omicron’s intrinsic mildness was a lucky strike for us. If the next variant is an offshoot of Delta, that gift would be revoked, and everything will rest on vaccines (and infection-acquired immunity) again.
Finally, a very interesting randomised controlled trial into vaccines’ impact on sporting performance concluded over the weekend, with striking results...
Researchers took elite athletes, matched on age and Grand Slam titles, and assigned them to one of two conditions:

Novax ⛔️
Needal 💉

Being unvaxxed was associated with:
• Extended periods of inactivity
• Loss of shared Grand Slam record
• Deportation

Get vaxxed, folks 👍
And with that, I’m off on holiday for a week 👋

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More from @jburnmurdoch

Jan 20
The steepness of Omicron’s rise and fall in South Africa really is something to behold.

Here’s Gauteng first, where it all began.

Cases, test positivity, admissions, deaths and excess deaths too all down almost as steeply as they rose, and in much less time than past waves.
We’ve all got used to comparing the height of "new daily x" charts over the last couple of years, but at the end of the day it’s not just wave height but also wave duration that determines the ultimate toll on public health, so it’s worth looking at each wave cumulatively...
And here we are:

*Daily* cases peaked close to Delta, but shorter wave means total cases much lower

With more acute outcomes it’s striking:
• Less than 40% as many hospitalisations
• 10% as many deaths, and excess deaths lower still

These numbers will rise, but not by much
Read 12 tweets
Jan 17
Lots of people asking if UK cases are really falling, or have we just exceeded testing capacity or seeing effect of the pause in requiring confirmatory PCRs

By comparing ONS infection survey to dashboard cases, we see the trends match. The fall in cases in recent days is real ✅
There is of course some variation, e.g prevalence in Yorkshire still climbing when reported cases began falling, but even there we clearly see a slowdown in ONS series, and looking across all regions it’s clear that those minor discrepancies are the exceptions that prove the rule
On top of that, new cases in hospitals — where testing capacity is certainly not limited — are flat or falling in all UK nations & regions, with that peak coming a week or so after cases turned, exactly as expected. Absolutely zero reason not to trust that infection peak is real.
Read 5 tweets
Jan 11
The Netherlands is one of the most interesting places for tracking the divergence of cases from more acute outcomes as Omicron takes over

Timing of its winter Delta wave meant numbers rose *and fell* before Omicron took off, so any rise now can reasonably be attributed to Omi
This is in contrast to places like the US where Omicron is piggy-backing on top of a fierce winter Delta wave, making it tricky to know whether it’s Omicron or Delta that’s sending hospitalisations ever higher
(Updated chart for all US states here)
Read 5 tweets
Jan 6
NEW chart for US Covid-watchers:

Key question with Omicron wave is whether severe disease — hospitalisations & ICU — decouples from cases.

In the UK it has, but there are signs the US decoupling is weaker, perhaps due in part to lower vax rates.

Track it here for every state:
Here’s a quick recap of how to read these charts:

Black dotted line is peak level for each metric before Omicron arrived.

Crossing that line means a new record has been set in recent days.

I’ve put a little coloured circle below the name of each state to indicate new records.
For example, almost all states in the north-east have set new records for cases in recent days.

New Jersey, Maryland and DC have also seen hospitalisations hit an all-time high, and the latter two are now also at record Covid ICU occupancy.
Read 8 tweets
Jan 4
NEW: first thread of 2022 is an Omicron situation update, starting with a detailed look at UK hospitals, before going international.

Let’s start with severity, and the most important chart:

Despite steep rises in cases and patients, the number on ventilators has barely risen.
I’ve adjusted for lag between positive test and severe disease, so the divergence between patients and ventilated is a marked difference between this and previous waves when they were in lockstep.

The link between cases and severe disease has significantly weakened with Omicron.
We also continue to track "excess ICU pressure" — total number of people in ICU, for any reason, Covid or otherwise, compared to past winters:

Latest data show that the number of people in London ICUs has fallen in recent weeks, and is not following the same path as last winter.
Read 41 tweets
Dec 23, 2021
NEW: situation update from Gauteng, where cases, test-positivity and admissions are all now falling (no, this is not driven by testing capacity/behaviour or by migration).

Deaths and excess deaths still rising, but based on timing of peak will not come close to Delta levels.
Another way of looking at same data:

Cases climbed to 90% of their Delta peak, but admissions peaked at 50% and deaths will peak below 50%, demonstrating how immunity — both acquired since Delta, and differentially present among Omicron cases — reduces rates of severe disease.
As ever, a big thanks to the brilliant people at @nicd_sa who make this data available, and to the likes of @lrossouw and @tomtom_m who have consistently been providing invaluable data and commentary from South Africa.
Read 4 tweets

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