top of page
Search

More on the illusions of vaccine efficacy

Updated: Oct 24, 2022

I have previously provided examples of how the illusion of efficacy over a period of time can be created for a vaccine intended to avoid getting infected with a virus. For example, this article shows that if the vaccine is a placebo (i.e. has no effect at all) it will appear to be effective if there is a delay in reporting infections of those vaccinated. But it is just an inevitable statistical illusion. In this article I showed the same illusion is created if those infected shortly after vaccination are classified as unvaccinated. I also produced a detailed video about it and its implications in assessing Covid vaccine efficacy and safety.


In assessing the efficacy of Covid vaccines in observational studies (such as in the large Israel study which claimed 95% efficacy of the Pfizer vaccine) it is now standard to assume that the vaccine takes 14 days to 'work' and hence to classify a person as 'unvaccinated' within 14 days of vaccination. But, as the previous example shows, such an approach inevitably exaggerates efficacy.


Because it is such a critical issue and lots of people still don't 'get it' I have tried to explain in the simplest way possible in this short video why assuming a person is 'unvaccinated' until 14 days after vaccination is such a problem:



The video also shows how vaccine effectiveness in observational trials is further exaggerated if the unvaccinated are less likely to get tested for the virus than the vaccinated (as happened in the Israel Pfizer study).


3,923 views11 comments

11 Comments


nick canning
nick canning
Aug 12, 2023

Vaccine efficacy: statistical illusion or biochemical reality? A dispute between SI and BR

SI: Prof Fenton et al show that vaccine efficacies as high as 95% can be produced by uncorrected systematic biases in the analysis of observational data, even when the true efficacy is 0% (or even negative). Under these circumstances, efficacy decreases with time towards the true value. They claim this may explain the observed waning and the need for vaccine boosters. If true, “vaccine protection” is merely a statistical illusion.

BR: But we can measure antibodies to the antigen provided by the vaccine, and follow their development over time (also T cells and other markers of an activated immune response can, and have been, meas…

Like

I presume your calculations are showing "relative risk reduction" (RRR)? But from what I've read, we need to know the "absolute risk reduction" (ARR) in order to establish efficacy in the real world, and that the drug companies tend to publish RRR so that their product looks far, far better than it is in reality. Here are a few articles to illustrate what I mean: Dr Peter Doshi's paper - https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4125239 The Lancet article - https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(21)00069-0/fulltext Medicina journal - https://www.mdpi.com/1648-9144/57/3/199/htm

Like

I understand this explanation , it has blown my mind! Can you explain how this issue should be addressed? What is the correct way to perform the analysis? I guess there are statistical methods to address this? Thanks for your time.

Like
Nir Tsabar
Nir Tsabar
Oct 27, 2022
Replying to

I believe that simply, counting deaths in the ''jab group'' from the first day of the jab, will make much more sense. However, I also believe that a randomized controlled trial (RCT), with a large enough number of participants that are at risk of dying is the only real correct way to know. Avoiding decent RCTs for COVID-19 vaccines is a huge mistake.

Like

Can anyone show me info regarding the imbalanced testing rates in the cited Israel study? I believe this is it: https://www.nejm.org/doi/10.1056/NEJMoa2101765 I don't see any info on testing rates, and as far as I know the data is not public.

Like
Norman Fenton
Norman Fenton
Oct 24, 2022
Replying to

It's all explained here with references: https://probabilityandlaw.blogspot.com/2021/05/important-caveats-to-pfizer-vaccine.html

Like

Very nice simple explanation even I can understand! :-)

Like
bottom of page