A vaccine so effective, you have to keep taking it over and over and over... that's how vaccines work - you keep taking the same vaccine over and over because it stopped working because the virus is different but if we take more of the vaccine that stopped working and it will work against this new mutant virus because vaccines get tired and sleepy and you have to give them a boost to wake them up again...and stop asking questions, and just do it ok? It worked the last time which is why we have to do it some more...

nope, nothing dodgy in that logic. Nothing to see here, move along....