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It's great that the UK has delivered 11M COVID vaccine doses, but let's talk about the efficacy of one dose of the Pfizer vaccine...
This thread is 17 tweets long, but the TLDR is that efficacy appears to be ~50% for Over 60s and the claims that it's 89%+ are *embarassing*
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This thread is 17 tweets long, but the TLDR is that efficacy appears to be ~50% for Over 60s and the claims that it's 89%+ are *embarassing*
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Pfizer themselves have stated that a single dose of their vaccine is 52% effective, but until recently the real-world data has been limited
Thanks to Israeli researchers we can now get insights into the true efficacy of a single Pfizer vacicne dose... https://www.medrxiv.org/content/10.1101/2021.01.27.21250612v1.full
Pfizer themselves have stated that a single dose of their vaccine is 52% effective, but until recently the real-world data has been limited
Thanks to Israeli researchers we can now get insights into the true efficacy of a single Pfizer vacicne dose... https://www.medrxiv.org/content/10.1101/2021.01.27.21250612v1.full
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The Chodick et al paper, (linked above), used data from Maccabi Healthcare Services, an Israeli medical insurance provider, and provides the strongest real-world data so far
The study ran from December 19th to January 15th, and examined medical records of 503,875 individuals
The Chodick et al paper, (linked above), used data from Maccabi Healthcare Services, an Israeli medical insurance provider, and provides the strongest real-world data so far
The study ran from December 19th to January 15th, and examined medical records of 503,875 individuals
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Chodick et al covers a period of 24 days from first dose. They found no impact until Day 12, so they analysed the *difference* between Days 1-12 and 13-24
This is relevant because UK studies have ignored the first period and interpolated results based on the 2nd period alone
Chodick et al covers a period of 24 days from first dose. They found no impact until Day 12, so they analysed the *difference* between Days 1-12 and 13-24
This is relevant because UK studies have ignored the first period and interpolated results based on the 2nd period alone
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It is notable that findings in Chodick et al are based on PCR tests, with no differential between syptomatic/asymptomatic cases
However, they also note that they found efficacy in the Over 60s to be 44.5%, suggesting *potential* for a slightly reduced efficacy in the elderly
It is notable that findings in Chodick et al are based on PCR tests, with no differential between syptomatic/asymptomatic cases
However, they also note that they found efficacy in the Over 60s to be 44.5%, suggesting *potential* for a slightly reduced efficacy in the elderly
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Another study of the impact of Israel's vaccination program is provided by Rossman et al, which doesn't analyse dosage efficacy but overall impact of the program
@segal_eran, a co-author of Rossman et al, is providing regular updates on the situation https://twitter.com/segal_eran/status/1357073473097658369
Another study of the impact of Israel's vaccination program is provided by Rossman et al, which doesn't analyse dosage efficacy but overall impact of the program
@segal_eran, a co-author of Rossman et al, is providing regular updates on the situation https://twitter.com/segal_eran/status/1357073473097658369
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Analysis by Rossman et al shows a 40.5% reduction in cases in the Over 60s cohort in the 3 weeks from the period January 11th - February 1st
Their first draft paper can be found below, and in their conclusion they refer to "first signs" of progress... https://github.com/hrossman/Patterns-of-covid-19-pandemic-dynamics-following-deployment-of-a-broad-national-immunization-program/blob/main/2021-02-03%20%20-%20Patterns%20of%20covid-19%20pandemic%20dynamics%20following%20deployment%20of%20a%20broad%20national%20immunization%20program.pdf
Analysis by Rossman et al shows a 40.5% reduction in cases in the Over 60s cohort in the 3 weeks from the period January 11th - February 1st
Their first draft paper can be found below, and in their conclusion they refer to "first signs" of progress... https://github.com/hrossman/Patterns-of-covid-19-pandemic-dynamics-following-deployment-of-a-broad-national-immunization-program/blob/main/2021-02-03%20%20-%20Patterns%20of%20covid-19%20pandemic%20dynamics%20following%20deployment%20of%20a%20broad%20national%20immunization%20program.pdf
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By January 11th, ~80% of the Over 60s cohort had received their first vaccination. This allows us to make a crude interpretation of real-world efficacy of one dose after 21 days
It is complicated by 2nd doses being delivered, but we can still assume "best case" from one dose
By January 11th, ~80% of the Over 60s cohort had received their first vaccination. This allows us to make a crude interpretation of real-world efficacy of one dose after 21 days
It is complicated by 2nd doses being delivered, but we can still assume "best case" from one dose
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If vaccine efficacy is 90% after 21 days, with 80% vaccinated we'd expect 8% of that cohort, (1 in 10), to remain suceptible. Add the 20% of unvaccinated and we should see a case decrease of ~72%
Applying the same equation with 50% vaccine efficacy, we'd expect ~40% decrease
If vaccine efficacy is 90% after 21 days, with 80% vaccinated we'd expect 8% of that cohort, (1 in 10), to remain suceptible. Add the 20% of unvaccinated and we should see a case decrease of ~72%
Applying the same equation with 50% vaccine efficacy, we'd expect ~40% decrease
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Notably the Rossman et al study describes a 40.5% decrease in cases, which points to the ~50% efficacy from one dose suggested by Pfizer and Chodick et al
There is the complication of the 2nd doses, and also lag to offset, but for simplicity we can assume they cancel out
Notably the Rossman et al study describes a 40.5% decrease in cases, which points to the ~50% efficacy from one dose suggested by Pfizer and Chodick et al
There is the complication of the 2nd doses, and also lag to offset, but for simplicity we can assume they cancel out
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You may have heard of a new UK paper, Hunter/Brainard, which appears to support the JCVI assessment of 89% by analysing the data from Chodick et al
However, there appear to be some significant flaws in that paper, which undermine it's credibility... https://www.medrxiv.org/content/10.1101/2021.02.01.21250957v1.full.pdf+html
You may have heard of a new UK paper, Hunter/Brainard, which appears to support the JCVI assessment of 89% by analysing the data from Chodick et al
However, there appear to be some significant flaws in that paper, which undermine it's credibility... https://www.medrxiv.org/content/10.1101/2021.02.01.21250957v1.full.pdf+html
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In their paper, Hunter/Brainard state...
"The data contained in this analysis were taken from Figure 1 in the pre-print by Chodick and colleagues (2021)"
Except Figure 1 of Chodick et al is a reproduction from the Pfizer trial, (Polack et al), and not the Israeli data
In their paper, Hunter/Brainard state...
"The data contained in this analysis were taken from Figure 1 in the pre-print by Chodick and colleagues (2021)"
Except Figure 1 of Chodick et al is a reproduction from the Pfizer trial, (Polack et al), and not the Israeli data
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Whilst the interpretation that Hunter/Brainard analysed data from the Pfizer Phase 3 trial, (Polack et al), could be due to a mistake in their paper, the conclusions they draw, and criticisms they make, do appear to refer to the Pfizer data and not the Chodick et al study
Whilst the interpretation that Hunter/Brainard analysed data from the Pfizer Phase 3 trial, (Polack et al), could be due to a mistake in their paper, the conclusions they draw, and criticisms they make, do appear to refer to the Pfizer data and not the Chodick et al study
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If Hunter/Brainard analysed data from the Pfizer Phase 3 trial, this would explain how they came to the same conclusions as the JCVI
However, the data provided by Rossman et al clearly dispels any claim that 1 dose of the Pfizer vaccine provides 89% protection after 21 days
If Hunter/Brainard analysed data from the Pfizer Phase 3 trial, this would explain how they came to the same conclusions as the JCVI
However, the data provided by Rossman et al clearly dispels any claim that 1 dose of the Pfizer vaccine provides 89% protection after 21 days
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There are *many* other criticisms that could be made of the Hunter/Brainard paper, aside from them apparently analysing the wrong data, but the "real-world" data from Israel explicitly dispels any credibility of claims that 1 dose of Pfizer's vaccine provides 89% protection
There are *many* other criticisms that could be made of the Hunter/Brainard paper, aside from them apparently analysing the wrong data, but the "real-world" data from Israel explicitly dispels any credibility of claims that 1 dose of Pfizer's vaccine provides 89% protection
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I don't know whether Pfizer's vaccine only offering ~50% protection from one dose would change the UK's delay strategy
I'm just a computer hacker with too much time on my hands, but data from Israel suggests the impact of UK's vaccination strategy will be less than forecast
I don't know whether Pfizer's vaccine only offering ~50% protection from one dose would change the UK's delay strategy
I'm just a computer hacker with too much time on my hands, but data from Israel suggests the impact of UK's vaccination strategy will be less than forecast
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It goes without saying that 50% protection is infinitely better than no protection...and Chodick et al not differentiating between symptomatic/asymptomatic infection means it may well reduce severe illness...but Rossman et al will deliver more findings on that soon
/ENDS
It goes without saying that 50% protection is infinitely better than no protection...and Chodick et al not differentiating between symptomatic/asymptomatic infection means it may well reduce severe illness...but Rossman et al will deliver more findings on that soon
/ENDS
PS: this analysis has been broken down for a Twitter thread, so it lacks nuance and I strongly recommend reading the studies for yourself
Finally, this tweet is very useful for contextualising the vaccine coverage required to achieve herd immunity
https://twitter.com/MarylouiseMcla1/status/1357107437686300674
Finally, this tweet is very useful for contextualising the vaccine coverage required to achieve herd immunity
https://twitter.com/MarylouiseMcla1/status/1357107437686300674
