Is there a verb meaning "to make likely or probable" or "to make unlikely or improbable"?
I'm more in need of the latter, but I assume that if the former exists, the latter might too.
Edit: I'm looking for something that is a less-absolute form of prevent. Example:
The old jacket at least prevented me from catching a cold.
is too absolute. So, instead I'm trying to use a word meaning "to make unlikely or improbable".
The old jacket at least [———]ed me from catching a cold.