Coronavirus

[Simon B]

I do have to confess to not really understanding how any vaccine producer can say that this or that is 95% effective since these are not 'challenge trials'. They take blood samples at the screening...that's to see if one already has antibodies for Covid (I don't get told) but not at any other time. All that they can say is that out of, say, 1000 people split 50:50. that of the placebo group x% got Covid but in the vaccine group 0% got Covid. But that really doesn't take into account the likelihood of getting it in the first place.

In a properly conducted Randomised Control Trial, what could lead to a correlation between being placed in the placebo vs vaccine groups versus the risk of encountering a viable virus attack (a more precise formulation of "getting it in the first place")?

The answer should be: nothing. The very definition of a properly conducted trial - remove or account for confounding factors. Then, the larger the number of people who over time have an infection the more improbable it becomes that the explanation for x% of them having had the placebo is anything other than that the vaccine is y% effective.

Put it another way: If 100 people who had the placebo had an infection, then the probability that 100 people who had the vaccine were similarly exposed should tend to 100% in a properly conducted trial. So what else could the result mean?

In the finer detail, the prior (to the existence of the experiment) probability of any random subject getting infected partly determines how many people must be observed infected before the result can be declared with a certain quantifiable confidence - it comes down to maths.

But maybe all of this is obvious and really you're asking a different question?

Either way, everyone willing to participate in trials is to be be thanked. There's really no other way to find out what's what.

[Anastasius]

Thanks for your posts on this which are really interesting.
Which trial is it you are in, I tried looking up thread but couldn't see.

PM sent, TS

It's one that doesn't require -80 C storage and so of much more benefit to third-world countries

[Anastasius]

Thanks Simon. It's much as I thought. So in extremis, if all those who had the active vaccine were to isolate (assuming all testing negative) on a desert island for a year and didn;t catch Covid then that's a 100% success rate. Albeit an unrealistic scenario. In my case, effectively self-isolating due to lifestyle anyway, the chances of me getting Covid are, thankfully, low regardless as to whether or not I have the placebo. It's all in the numbers.

[Simon B]

Thanks Simon. It's much as I thought. So in extremis, if all those who had the active vaccine were to isolate (assuming all testing negative) on a desert island for a year and didn;t catch Covid then that's a 100% success rate. Albeit an unrealistic scenario. In my case, effectively self-isolating due to lifestyle anyway, the chances of me getting Covid are, thankfully, low regardless as to whether or not I have the placebo. It's all in the numbers.

I see what you're getting at. In extremis, that could happen, as could all other confounding scenarios. However, as long as the central tenets of a control trial are maintained (the participants don't know which group they're in and the composition of both groups is statistically speaking the same) the probability of some differential behaviour between groups, which would thus have to occur purely by chance, rapidly tends to zero as the number of participants increases.

There is a potential problem with a vaccine where participants are expecting to have a reaction to the injection. This, I believe (this not being my field) is why some trials give a vaccine for something else as a "placebo" in the hope that it induces similarly noticeable symptoms. Otherwise, there's one obvious causal mechanism for differential behaviour straight away... Given the range of human behaviour from cautious to blasé and the size of the trial, the chances of this accounting wholly for the whopping differentials in the recent vaccine trial results is pretty much nil, but there is a risk it might be skewing the numbers a bit. This will have occurred to someone before - which is where these unfashionable things like pesky experts who know stuff and tedious bureaucracy like peer review and regulatory committees are supposed to keep an eye on things!

That aside, every statistical experiment you can conceive of has some pathological case - e.g. the Higgs Boson may yet still not exist. This is now considered to be very very very very very unlikely. At one stage it was accepted to be merely very very unlikely and that wasn't good enough so the experiment continued. Eventually you have to draw the line somewhere. The only absolute certainty is that nothing is absolutely certain. As you say, it's all in the numbers.

[johnb]

I've done a trial version of my UK Cases by Local Authority Maps where on both the Cases/100k and the Increases/Decreases maps you are able to toggle between the current week and the previous week being displayed.

The difference is particularly noticeable with the Increases/Decreases map - showing signs that the lockdown is having some effect.

This version uses the same URL as before:

https://app.powerbi.com/view?r=eyJrIjoiZDkxMTQwYTAtZGI2MS00MjI2LWJkYzEtNDQ3ZjM0ZDczZTE0IiwidCI6IjQyMTI4YmIwLTJjZjgtNDY3MC1iNzRhLWZhNDlmNGJkMDQzZSJ9

Let me know what you think.

[Dave2002]

I've done a trial version of my UK Cases by Local Authority Maps where on both the Cases/100k and the Increases/Decreases maps you are able to toggle between the current week and the previous week being displayed.

The difference is particularly noticeable with the Increases/Decreases map - showing signs that the lockdown is having some effect.

This version uses the same URL as before:

https://app.powerbi.com/view?r=eyJrIjoiZDkxMTQwYTAtZGI2MS00MjI2LWJkYzEtNDQ3ZjM0ZDczZTE0IiwidCI6IjQyMTI4YmIwLTJjZjgtNDY3MC1iNzRhLWZhNDlmNGJkMDQzZSJ9

Let me know what you think.

Very helpful. Does seem to indicate a slight improving of the situation. Thank you.

[Anastasius]

Thanks John. What I find really interesting is to look at where I used to live (Herefordshire) where hitherto number of cases were very low. Now they are increasing rather fast and given the county and the demographics one wonders if there was some 'event' that sparked this off. Ditto Wealden. Wouldn't it be great if Test and Trace was able to work back and determine the cause of the spike and so maybe be able to give guidance?

[oddoneout]

Thanks John. What I find really interesting is to look at where I used to live (Herefordshire) where hitherto number of cases were very low. Now they are increasing rather fast and given the county and the demographics one wonders if there was some 'event' that sparked this off. Ditto Wealden. Wouldn't it be great if Test and Trace was able to work back and determine the cause of the spike and so maybe be able to give guidance?

Isn't that where local involvement is important?

[Anastasius]

Isn't that where local involvement is important?

Absolutely and spot on. How I wish the Govt would think of that ?

[Serial_Apologist]

Absolutely and spot on. How I wish the Govt would think of that ?

Try telling that to the young fogeys now running everything everywhere... and they'll never believe you...

[Frances_iom]

a centralised system allows great control in the hands of a few - for some leads to riches way beyond their ability, for others it is the power to be 'king of the World' or in BJ's case cock of the dunghill that he will leave to his successors

[Dave2002]

a centralised system allows great control in the hands of a few - for some leads to riches way beyond their ability, for others it is the power to be 'king of the World' or in BJ's case cock of the dunghill that he will leave to his successors

They will leave him on top until the dung hill is somewhat less full of ..... and difficult to manage. Then swoop down.

Nobody but an idiot, or a genius would want the position right now.

[oddoneout]

Absolutely and spot on. How I wish the Govt would think of that ?

'Government' and 'think' might be a clue? The other big problem is that there's nothing in it for Tory crony donors cf the Serco version and similar troughs.
This is about another issue but the picture is applicable to this topic as well https://www.theguardian.com/commenti...rnment-cartoon

[Anastasius]

OK. After much thought, I wrote an email to the company with some suggested ways to improve the recruitment process for the trial...you know, little things like 'Bring PhotoID' and the lack of a proper physical examination prior to being given the vaccine - as set out in their documentation provided to the regulatory authority as to the ethics of the trial. And if they are cutting corners here, what else might they be fudging ? Little things like that.

I waited. And waited. And waited. No response. I contacted the company running the trial..."Is this email address given to participants actively monitored?" "Don't know'. There is no way of contacting the head office in the UK. All telephone calls go through to their call-centre and no further. Filling in a contact form goes unanswered. I also noticed something else.....

Us volunteers were also given access to an App called Patient Cloud by Medidata. This app being crucial for determining (a) any side-effects (especially after a sample size of 15,000 volunteers) and (b) whether or not it was effective by logging any Covid symptoms etc. Basically, it doesn't work. Check out the many negative reviews on Google PlayStore.

I worked in IT. I know how critical programs like this are supposed to work. I know a poorly implemented CoS when I see one. I can accept that the failings in the actual trial process could simply be put down to human error and the sheer number of volunteers being processed for the trial. But when the key component required to measure and validate the efficacy (on which much is relying) is such an appalling Horlicks then I'm going to try my damndest to get the media involved. Any potential journalists or contacts gratefully received ....by Message if need be.

This is yet another cock-up by HMG.

[gurnemanz]