It's almost as if it was designed this way. Traditional vaccines inject you with a deactivated virus. What your immune system then does is it studies the virus in something akin to a laboratory. It takes the virus apart bit by bit and creates antibodies to each piece of the virus. This creates a robust immunity. Even if one or two of the proteins change through mutations, the body will likely still have immunity through antibodies to the remaining proteins. Guess what the geniuses at PFizer did with the mRNA vaccine? To rush it out quicker they had mRNA code for only one out of four covid proteins. That proved to be woefully inadequate as far as immune protection goes. And what's more, having such homogenous antibodies in billions of people makes antibody dependent enhancement a real possibility. In future 'booster' shots (they'll call them boosters, but really they're entirely new vaccines) they'll have mRNA that codes for the remaining proteins of the virus.