So if you understand that 95% efficacy means that 95% of a cohort will be protected, surely you understand that this means 5%, or 1 in 20 will not be protected?
If it wasn't so, and that 5% had some level of protection, then the efficacy would be higher.
You can't apply an efficacy rating to a single person, that's not what it is intended to measure or convey. It is a community measure assuming ideal conditions. A vaccine will provide a wide range of protection. Some will be fully, or 100% protected, many somewhat less protected, some not at all.It doesn't mean that. A 95% efficacy means that the chance of a vaccinated person getting Covid is 95% less than someone who is not vaccinated.
Yes, once you start to consider the effects of public health measures on outcomes, then you need to speak in terms of vaccine effectiveness, and not efficacy.here are other public health measures and other reasons that will reduce the risk further so only a % of the 5% will actually catch Covid and even then might not be severe.
You can't apply an efficacy rating to a single person, that's not what it is intended to measure or convey. It is a community measure assuming ideal conditions. A vaccine will provide a wide range of protection. Some will be fully, or 100% protected, many somewhat less protected, some not at all.
Yes, once you start to consider the effects of public health measures on outcomes, then you need to speak in terms of vaccine effectiveness, and not efficacy.
Well it is Friday.I am hungover!....
Efficacy = what is the desired effect usually in a controlled environment
Effectiveness = what happens in the real world
So, a drug might have 95% efficacy but be 90% effective in the real world.
I might be wrong too.
If you click on the links on the Twitter above you can see all the reports to date, and a plethora of references to back up the assumptions made.Thats my understanding as well. I think Philip Nolan is just guilty of phrasing something carelessly as I doubt they have modelled the scenario he described. It is just worrying that the guy in charge of modelling made a statement that because of 95% vaccine efficacy, 5% of vaccinated elderly people are at risk of catching covid. He then backed it up with actual numbers of 25,000 out of 500,000 vaccinated people could get covid. This is simply wrong as he is assuming 100% attack rate.
It would be good to see the complete model released rather than tweets. At the very least they should be able to provide the basic assumptions made under each scenario.
If you click on the links on the Twitter above you can see all the reports to date, and a plethora of references to back up the assumptions made.
Its heavy reading btw, and a lot of cross referencing and dead boring.
It's all new given the speed of transmission since it began they have achieved quite a bit, if I knew reports were in the public domain I would have read them last and this year, but you would expect them to run more scenarios and show different results by changing key variables, a sensitivity analysis I think they call it.So they didn't provide a nice one page summary???
Thanks. I might have a look over the weekend but I don't think I have the attention span to be honest! I will continue to make unsupported accusations of flawed modelling as it is the lazier option!
By the way, I should state that I am in awe of what these guys produce from a modelling point of view. But I strongly believe that models work best when they are completely open to scrutiny and are not black boxes that only the people who designed them know how they work. We had a whole financial crisis built on black box models. It's good if they are publishing everything. I hope the academic and public health world step up and voice their opinions.
No you are right.Efficacy = what is the desired effect usually in a controlled environment
Effectiveness = what happens in the real world
So, a drug might have 95% efficacy but be 90% effective in the real world.
I might be wrong too.
That doesn't make sense, 0.74 % to 0.4% is actually a 50% reduction not 0.7%, !! Are you sure you have your figures correct. These don't sound like Pfizer figures anyway ?The Pfizer trial found an infection rate of 0.74% in the placebo group and 0.4% in the vaccinated group.
Therefore, the vaccine reduced the infection rate by 0.7%.
Should that be 0.04%?The Pfizer trial found an infection rate of 0.74% in the placebo group and 0.4% in the vaccinated group.
Therefore, the vaccine reduced the infection rate by 0.7%.
Scaled up this means an efficacy rate of 95.05% (0.7 / 0.74)
So if you understand that 95% efficacy means that 95% of a cohort will be protected, surely you understand that this means 5%, or 1 in 20 will not be protected?
If it wasn't so, and that 5% had some level of protection, then the efficacy would be higher.
Should that be 0.04%?
These don't sound like Pfizer figures anyway ?
Lucky guess on my part.Yes it should. I have amended post.
I wouldn't be so sure of that, looking back to February they over egged the forecasts too and the reality, while still terrible were a good 30% lower.In any event, NPHET don't believe any of these pessimistic scenarios are at all probable or we'd all be back doing laps of our 2km radius.
Yep and the initial trial size was 35,000 the additional numbers were for other minorities, but I also know that production was still started based on the original and in September 2020.Phase 111 of the Pfizer trial enrolled 43,661 people half of whom received a placebo and the other half were vaccinated.
There were 170 confirmed cases of which 162 (0.74%) were in the placebo group and 8 (0.04) in the vaccinated group.
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