NEW: @UKHSA study finds Pfizer booster is extremely effective against symptomatic infection, both compared to the unvaccinated and to those with 2 doses…

Whether first 2 doses were AZ or Pfizer, a Pfizer booster sends vaccine efficacy up to 93-94% 💪 Image
Study was on people aged 50+, comparing those boosted ~5+ months after dose 2, to those @ 5+ months unboosted.

AZ efficacy was 61% after dose 2, waning to 44% @ 5 months.

Pfizer was 82% after dose 2, waning to 63% @ 5 months.

2 wks after Pfizer booster, both groups -> 93-94%!
Best way to think about booster impact is not to look at going from 44 to 93 with AZ, i.e roughly doubling, but invert the numbers and go from (100-44) to (100-93), i.e from relative risk vs unvaxxed of 56% to just 7%

That’s an 87% increase in protection *relative to two doses!* Image
More importantly, level of protection after a booster is *much higher* than it was even at peak level just after second dose.

For AZ, relative risk just after dose 2 was 39%, now it’s 7% — an 82% reduction.

For Pfizer, RR just after d2 was 18%, now it’s 6% — a 67% reduction.
In other words, a booster isn’t just topping us back up to where we were after we got our second dose (and remember how invincible that felt?), it’s taking us to higher levels of protection than we’ve ever seen.
Of course, big question is whether we’ll look back on this as first in a regular series of boosters, or the 3rd dose of a three-dose vaccine.

The higher levels of protection hint at this being a new dose rather than just a recurring top-up, but more time and research are needed.
One more note: the new study (and all numbers I’ve quoted) are specific to symptomatic infection with the Delta variant.

And finally, a link to the study itself:…
Oh, and even though this study only looked at efficacy against infection, not hospitalisation or death, we would strongly expect the same pattern to emerge there, even if only as a function of infection risk falling (and thus fewer people being susceptible to severe disease).

• • •

Missing some Tweet in this thread? You can try to force a refresh

Keep Current with John Burn-Murdoch

John Burn-Murdoch Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!


Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

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. Image
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 Image
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

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!


0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy


3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us on Twitter!