Actually that is a false premise.
However, vaccines can become less and less effective as a virus changes. I wouldn’t take last year’s flu vaccine this year, for example...and even that can be a guess as to which strains will be the most dominant year to year.
Why take a flu vaccine at all? The very same BS is told to us every year as that with the Wuhan flu. “I get the vaccine(flu) every year, I get the flu, but it is a much milder form” Just like the Covid vaxx, it is a lie told to ourselves and to others.