"Hey, anti-vaxxer nutjob: Why don't you want to take the vaccine?"
The Burden of Proof
First of all, the premise of the question is a little off-balance. It's not my job to explain why I *don't* want ingest something into my body. Especially not an industrial product from a factory.
Consuming an industrial product is not the de-facto condition of humanity, from which all else is a deviation. It's quite the opposite. The baseline condition of a human being is to live naturally, as one is. Consumption of industrial products is the deviation.
You can argue that this particular product is good and people should take it; but it's wrong to begin from the premise that it's WE who have to explain ourselves. We don't. You do. If you want me to ingest an industrial product, then the onus is on YOU to explain why.
And when we get into the subject of potential *dangers* of said product, again the burden of proof is NOT on me to prove that it's dangerous. The burden of proof is on *you* to prove that it's safe.
"But it's safe! The SCIENTISTS tested it, and concluded that it was SAFE, and the GOVERNMENT approved it. What are you complaining about?"
The problem is, *Reality* does not come from the proclamations of governments, or universities, or any group of people. Reality is what Reality is. A government can't make the Sun rise in the west, or gravity fall upwards, just by proclaiming it. And they can't make a medical *experiment* become "not an experiment anymore" just by proclaiming that it's no longer experimental. These needles are EXPERIMENTS, and no jumble of words and papers and approval-stamps from any scientist, university, or government agency can change that.
Here ye, Hear ye!