I don't think you can use this comparison with a heterologous vaccine. In fact, vaccines could only be manufactured in quantity on large animals in order to extract, en masse, the "pus" produced to make vaccines [*], even when cultivated on humans (forbidden by the way). would have required enormous quantities.Uh ... but it is actually something well known. It's called heterologous vaccination. (I'm not saying it's good or not for COVID, I'm not competent) We've been talking about it for quite a while, including more classic vaccinations like memory BCG.
But biologically, an injected animal product retains its specificity and automatically becomes infectious, hence the inflammatory reactions. alleged immune.
[*] curiously these animals, overprotected by antibodies, were then slaughtered.
Weird, you said weird, how strange!