Since when have you believed that any vaccine could stop you being infected with any particular infectious agent? Vaccines cannot stop you from catching anything. They don't work that way. A vaccine can't physically stop you from inhaling, contacting or ingesting a virus or bacterium, etc. It isn't possible.
The vast majority of people who contract covid and are confirmed with it, experience not a lot more than a cold/flu type symptoms and get on with life within days.
The PCR test, whilst we are on the subject, is an incredibly sensitive test and from what I have read seems to be able to pick up tiny amounts of virus, even in people who have a very low viral load, recovering/un-infectious or totally asymptomatic.
I didn't say I believed a vaccination could stop you being infected did I?