We know the az vaccine is 70% effective for 12 weeks.
We also know Pfizer one is 90% for 21 days. Now surely to god we can assume its not going to lose all its immunity within 12 weeks?
The British medical board have far more data than the public and have decided thats what we should do.
Good enough for me
What I think people need to know is that it's 70% effective at preventing infection. However - unless I've read it incorrectly - it's basically 100% effective at stopping serious illness even if you do catch it.
So, from what I can gather, it works in a similar way to how variolation used to work with smallpox - you can still technically catch the virus but its' effects would be mitigated dramatically.
But the data is so weirdly expressed that it's hard to be sure. If that is the case, it needs to be expressed 1000x more clearly, because people would be delighted if that was the case. If the vaccine 100% 'downgrades' COVID to what would then be just a fairly hard cold, then everyone would be on board.