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Since the UK plan to delay the 2nd Covid vaccine from 3 weeks to 12 weeks was announced, I've felt VERY uneasy.
My concerns are principally related to the Pfizer vaccine.
Having now read the original paper in the New England Journal of Medicine, I'd like to set out my concerns.
My concerns are principally related to the Pfizer vaccine.
Having now read the original paper in the New England Journal of Medicine, I'd like to set out my concerns.
It has been suggested that there is unpublished data for the Oxford-AstraZeneca vaccine to support a 12 week gap between doses.
Accordingly, I reserve judgement on that vaccine until this data appears, but I do want to see that data.
Accordingly, I reserve judgement on that vaccine until this data appears, but I do want to see that data.
Over the course of the last few days, I've read many helpful Tweets and Twitter threads by such as:
@farrell_katrina @BMAScotland @Tanya_Marlow @PaulBieniasz @helenamckeown @EmergMedDr @HelenRSalisbury @StFilansDream @krishgm @Nicola_Yeo @doctorcaldwell @toca63 & @DoctorChrisVT
@farrell_katrina @BMAScotland @Tanya_Marlow @PaulBieniasz @helenamckeown @EmergMedDr @HelenRSalisbury @StFilansDream @krishgm @Nicola_Yeo @doctorcaldwell @toca63 & @DoctorChrisVT
Before I go any further, let me stress that I am enthusiastically both pro-science and pro-vaccines.
Indeed, my unease arises from a direct conflict between science and the proposed UK vaccine strategy.
I think it is a well intentioned but reckless gamble.
Indeed, my unease arises from a direct conflict between science and the proposed UK vaccine strategy.
I think it is a well intentioned but reckless gamble.
I had read lots of reports in recent days, related to the Pfizer vaccine.
First key question. How effective is one dose?
A friend steered me towards an article in @bmj_latest which stated one dose was 52% effective. https://www.bmj.com/content/371/bmj.m4826
First key question. How effective is one dose?
A friend steered me towards an article in @bmj_latest which stated one dose was 52% effective. https://www.bmj.com/content/371/bmj.m4826
Yesterday, I was surprised when @NicolaSturgeon said that the short term efficacy of the Pfizer vaccine after the first dose was 90%.
But the BMJ said 52%, where was the 90% figure coming from?
I am indebted to @patrickharvie for this response. https://twitter.com/patrickharvie/status/1346202413754159106?s=20
But the BMJ said 52%, where was the 90% figure coming from?
I am indebted to @patrickharvie for this response. https://twitter.com/patrickharvie/status/1346202413754159106?s=20
If in doubt (and I was), go to the source.
I read the original Pfizer vaccine paper which appeared in the New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa2034577
I read the original Pfizer vaccine paper which appeared in the New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa2034577
A key point to note in the Discussion section is:
"The study was not designed to assess the efficacy of a single-dose regimen."
The key data is contained in this graph, with the figures in a table at the bottom.
"The study was not designed to assess the efficacy of a single-dose regimen."
The key data is contained in this graph, with the figures in a table at the bottom.
The 52% figure quoted by the BMJ is actually 54.2% and relates to the people who developed Covid symptoms in the 3 week gap between doses.
39 in the vaccine group.
82 in the placebo group.
However, there are associated 95% Confidence Intervals.
Low End: 29.5%
High End: 68.4%
39 in the vaccine group.
82 in the placebo group.
However, there are associated 95% Confidence Intervals.
Low End: 29.5%
High End: 68.4%
I don't have a background in Statistics, but as I understand it, this means you can be 95% confident that the efficacy after one dose is somewhere BETWEEN 29.5% and 68.4%.
That is quite a broad range.
That is quite a broad range.
So, where does the 90% figure come from?
That relates to people who developed Covid symptoms in the first 7 days after the 2nd dose had been given, but before it is believed to have had any effect.
The numbers are:
2 in the vaccine group.
21 in the placebo group
That relates to people who developed Covid symptoms in the first 7 days after the 2nd dose had been given, but before it is believed to have had any effect.
The numbers are:
2 in the vaccine group.
21 in the placebo group
The efficacy for this data is given as 90.5% (with a 95% CI range of 61% to 98.9%)
The health outcomes of 23 people during one 7 day period, seems like pretty thin (experimental data) gruel on which to gamble the health of an entire nation, don't you think?
The health outcomes of 23 people during one 7 day period, seems like pretty thin (experimental data) gruel on which to gamble the health of an entire nation, don't you think?
If I recall all my daily briefings correctly, the incubation period for Covid can be up to 10 days, related (in part) to the viral load to which you are exposed.
If so, overlaying a 10 day window, over a 7 day window has inherent uncertainties.
If so, overlaying a 10 day window, over a 7 day window has inherent uncertainties.
Additionally, factor in random chance.
Given those numbers, it wouldn't take much to skew them significantly.
Maybe it was an unusually lucky week for the vaccine group and an unusually unlucky one for the placebo group?
Given those numbers, it wouldn't take much to skew them significantly.
Maybe it was an unusually lucky week for the vaccine group and an unusually unlucky one for the placebo group?
Last night I watched an interview between @DrPaulOffit and @wolfblitzer on @CNNSitRoom
Dr Offit is a member of the @US_FDA advisory committee for Covid vaccine approvals. https://www.phillymag.com/healthcare-news/2020/12/15/covid-19-vaccine-questions-paul-offit/
Dr Offit is a member of the @US_FDA advisory committee for Covid vaccine approvals. https://www.phillymag.com/healthcare-news/2020/12/15/covid-19-vaccine-questions-paul-offit/
Wolf asked Dr Offit about the idea of giving one dose of vaccine to people as a priority, to spread the vaccine more widely.
I rewound my TiVo several times to note his response.
He said:
I rewound my TiVo several times to note his response.
He said:
âI donât support that at all. There was a period of time 3 weeks or 4 weeks when someone had one dose before they got a second dose, where there was some evidence of protection...
...but those were based on very small numbers and you donât know how long that efficacy would last. I think thatâs a bad idea.â
There seems to be a widespread belief that two doses of the Pfizer vaccine will result in 95% efficacy.
That is a misunderstanding of the science.
We ONLY know that 2 doses of the Pfizer vaccine, administered under the conditions of the trial, will deliver 95% efficacy.
That is a misunderstanding of the science.
We ONLY know that 2 doses of the Pfizer vaccine, administered under the conditions of the trial, will deliver 95% efficacy.
The graph in the Pfizer paper is spectacular, but most of the "good stuff" occurs after the 2nd dose has been given.
Without a clinical trial, there is no way to know how a single dose will behave between 21 days and 12 weeks.
It may track the graph, or level off, or fall back.
Without a clinical trial, there is no way to know how a single dose will behave between 21 days and 12 weeks.
It may track the graph, or level off, or fall back.
If you wait 12 weeks to give the 2nd dose, it's anyone's guess what the final efficacy will turn out to be.
You've got to ask yourself one question: "Do I feel lucky?" Well, do you, punk?
You've got to ask yourself one question: "Do I feel lucky?" Well, do you, punk?
I have an additional concern.
If people are being given the message that 1 month after they get the first dose of the Pfizer vaccine they are 90% likely to be protected, they may behave accordingly and recklessly.
That could be catastrophic.
If people are being given the message that 1 month after they get the first dose of the Pfizer vaccine they are 90% likely to be protected, they may behave accordingly and recklessly.
That could be catastrophic.
Best case scenario?
Everything works out fine and with the benefit of hindsight it looks like an inspired decision.
That is certainly possible, but we simply cannot know that at this point.
If this strategy is pursued, I really hope that is the outcome.
Everything works out fine and with the benefit of hindsight it looks like an inspired decision.
That is certainly possible, but we simply cannot know that at this point.
If this strategy is pursued, I really hope that is the outcome.
Worst case scenario?
The timing of the 2nd dose turns out to be critical.
During the extra delay before giving the 2nd dose, efficacy declines to some unknown (but fairly low) value.
As a result, the 2nd dose has only a marginal (and short-lived) effect.
The timing of the 2nd dose turns out to be critical.
During the extra delay before giving the 2nd dose, efficacy declines to some unknown (but fairly low) value.
As a result, the 2nd dose has only a marginal (and short-lived) effect.
As other countries make steady progress and gradually return to normality, the situation in the UK remains grim.
Public confidence in vaccines is severely damaged.
Anti-vaxxers have a field day.
Public confidence in vaccines is severely damaged.
Anti-vaxxers have a field day.
If we should be listening to anyone about how to deploy the @pfizer vaccine, shouldn't it be...Pfizer, who say:
'...there was "no data" to demonstrate that the protection offered by the first dose would be sustained after three weeks.' https://www.smh.com.au/world/europe/pfizer-biontech-warn-uk-against-plans-to-delay-second-vaccine-jab-20210105-p56rqj.html
'...there was "no data" to demonstrate that the protection offered by the first dose would be sustained after three weeks.' https://www.smh.com.au/world/europe/pfizer-biontech-warn-uk-against-plans-to-delay-second-vaccine-jab-20210105-p56rqj.html
I do not understand how the 4 UK CMOs can be so certain the strategy they are proposing is correct, based on such a tiny sliver of data, across such a narrow window of time.
What are they seeing in the data that Dr. Fauci (and many others) are not?
https://www.nytimes.com/2021/01/01/world/dr-fauci-advises-against-the-british-approach-of-delaying-a-second-dose-of-vaccine.html
What are they seeing in the data that Dr. Fauci (and many others) are not?
https://www.nytimes.com/2021/01/01/world/dr-fauci-advises-against-the-british-approach-of-delaying-a-second-dose-of-vaccine.html
