The mistake is in generalization. Lots of vaccines are at the same efficacy they've always been; some are losing effectiveness for a number of reasons (more resistant bugs; decreased herd immunity; the varicella vaccine looks like it might have been rushed to market, etc). You can't really say "vaccines" any more than you can say "medicine". I have more reasons than most to know stuff about this and I think you can safely say that, as a general rule, vaccines are highly effective at preventing disease. You cannot, however, say they are 100% effective.

As far as the age of the universe, the shift you've observed is due to theories being disproven through empirical observation. We went from "4 billion" to "10 to 20 billion" to "14 billion" to "13.5 billion" - and it's important to note that the "4 billion" number predates widespread discussion of The Big Bang Theory. Bit of a corner case, really, and if you were to focus on "tested theory" your range would be "10 to 20 billion."

Guy I went to high school with is an expert on CBMR, and I'm currently reading Tegmark; I recommend it. It's a light and easy read.