In the past, some substances were thought to be safe, but turned out not to be. The “it’s safe” period of time was longer than a year.
Ergo it is reasonable to assume that we can’t know all of the side effects of current novel vaccines. It doesn’t mean there will be any, but it doesn’t mean there won’t be either.
That’s how science works.
see, in that example, you made up a rule that anything you want will cause Z, but there's no actual scientific basis for the rule
you have to actually prove Y will do Z, you can't just claim something else did Z, therefore anything can do Z
Again, you lack a basic understanding of the scientific method.
to wit, you have not proven there is a good reason to worry about widespread significant long-term side effects of the COVID vaccines -- specifically, DDT is not a past example of a vaccine resembling any of the COVID vaccines
the lack of evidence pointing to widespread, significant, long-term side-effects so far, however, is evidence enough for us to lean in that direction
I do, however, support your right to avoid the vaccine, as well as your right to avoid any place or activity that requires those present to have it, so at least there's that