All three of your links show a lack of understanding of the word 'efficacy', which is defined as: "the ability to produce a desired or intended result".
If you have a clinical trial and everyone in the trial passes the clinical trial, that doesn't mean the vaccine is a magic cape that protects 100% against the virus.
It just means that the desired result in the trial was achieved.
If you have a clinical trial and everyone in the trial passes the clinical trial, that doesn't mean the vaccine is a magic cape that protects 100% against the virus.
It just means that the desired result in the trial was achieved.