Ahh yes, the veterinary doctor (as in dogs and cats) who released letters on Twitter and LinkedIn (the greatest scientific journals ever) predicting the end of the world!
Here’s why it’s a bunch of nonsense: https://zdoggmd.com/vanden-bossche/
He’s not the first person to postulate about the risks of viral escape caused by trying to vaccinate in the middle of a pandemic while mutations are still on the rise.
I am in no position to judge the situation but what he seems to be saying is there is a risk that the virus will mutate enough that it will evade the vaccine induced antibodies while at the same time the vaccine induced antibodies will limit the creation of innate antibodies by some mechanism e.g. crowded out by the artificial spike protein antibodies, or that the body tricks itself into thinking it is already working against the mutation when it isn’t.
Towards the end he discusses a little bit about his worry that with new variants still popping up, people may think they are immune but will end up becoming carriers for these mutations or catch this more severe strain and have limited natural ability to fight it. Again I’m in no position to judge just trying to absorb his postulate.