1) Mandatory childhood vaccinations against deadly infectious diseases are the most effective way to prevent the resurgence of the diseases in the U.S.
This one i correct. It provides everything a thesis statement needs.
The second one can be used as a supporting statement throughout the paper, but using it as a thesis statement is a bad idea.
Don't use the third one or a sentence ever like it in a paper. Never use "I" in a paper unless it's a personal narrative.