What, are you too use to google the basics of how vaccines work? I'm pretty sure I learned the basic idea in kindergarten (when exposed to viruses your body produces antibodies which help you fight subsequent infections, and clever people realised that if you use weakened/dead/inert viruses instead of the real thing you lower the risk of people dying before they can develop a full immune response). Some viruses change rapidly, meaning that you need to get a new vaccine for the latest strain every year.
What makes you think that this is "dodgy"? The fact that we don't have a single shot that cures all disease? Guess what, there are plenty of diseases we don't have cures for (e.g. Cancer) and even if we manage to find a cure then they will simply be replaced by new diseases (much like no one used to worry about cancer because they simply didn't live long enough to die of cancer), so jumping to the conclusion that there must be a conspiracy because there's no cure is insane,