top of page
Search

More on the illusions of vaccine efficacy

Oct 22, 2022
1 min read

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).


 
 
 

16 Comments


Guest
Oct 06

I came across this platform recently and decided to see how it works. The interface feels quite straightforward, and the navigation is easy enough for a first-time visitor. I also checked it on my smartphone and found the layout reasonably responsive. There are several features to explore, so I think understanding the platform first makes the overall experience much easier.


Cricket betting sites

Like

philipsalt
Oct 01

hindi varnmala ko bahut simple way mein explain kiya gaya hai. Bachchon ke liye yeh information kaafi useful hai.

Like

Guest
Sep 18

I tried goa game login doing a small withdrawal just to understand the process, and it was completed on the same day through UPI. Just wanted to confirm if the timing is always similar for everyone or if it depends on the amount and verification. I usually prefer keeping deposits low until I understand how everything works properly

Like

A to Z Alphabet
Jul 02

The a to z hindi alphabet comparison is very useful for English speakers. It gives a quick idea of how Hindi sounds relate to English alphabets.

Like

Guest
Jul 30, 2025

The trusted Escorts Service in Delhi is designed for those who want more than just looks – they want chemistry, connection, and quality time. Whether you’re looking for brief fun or something deeper, these services offer full satisfaction, complete discretion, and unmatched companionship at competitive rates.

Like

© 2026 Norman Fenton

  • Twitter
  • YouTube
  • LinkedIn
bottom of page