Vaccines aren't generally supposed to stop you getting sick, though (or even stop the spread of infection depending on the type of vaccine); they're supposed to stop you dying or getting severely ill and/or hospitalized if/when you do get sick.
Granted, they're not (yet) all perfect and 100% free of risks for the entire population (and may never be – until we reach Star Trek level), so it's a tough one. But it's about mitigating the risk of the alternative on a population level. No medical intervention is 100% successful as far as I know.
Even everyday drugs like aspirin aren't perfect. Millions take it every day with no problems, but it can be fatal in a small number of cases. Penicillin is also not 100% risk-free and can be fatal to a small number with severe allergies. But it has saved hundreds of millions of lives since its discovery. The death rate among soldiers from bacterial pneumonia apparently dropped from 18% in WW1 to 1% in WW2, following the introduction of penicillin. Now with antibiotic resistance increasing, the possibility of returning to a world without drugs like penicillin is a potential and real threat.
It's an important and difficult discussion to be had though and I believe the loss of even one human life in order to save millions (or to live in a world free of smallpox, or other deadly diseases most of us in developed countries are lucky/young enough not to remember, like polio, measles and TB) is not to be minimized and should not be taken lightly, so I'm upvoting your post. And I actually agree that it's right to raise concerns (and indeed we should) when dealing with such literally life-and-death matters, while also basing our decisions on evidence.
