You are asking why an already infected person who receives the vaccine may still be able to spread it? The virus is still able to spread while the body fights i

You are asking why an already infected person who receives the vaccine may still be able to spread it? The virus is still able to spread while the body fights it. In fact I'm not even sure there is a significant advantage of giving the vaccine to someone who already has the virus (as after all the vaccine teaches the body what the virus looks like and therefore how it can be tackled). This specific vaccine looks as if it simulates certain aspects of the virus, therefore not entirely necessary for someone who already has the virus I believe. But yeah - it's not like you get jabbed and you have instant immunity. Your body needs to learn to fight it, and then actually fight it - and if you already have it you are still infectious during this period.