I feel responsible

I feel responsible for the end of the world today.
No metaphor, killed a live vaccine kind of way.
Stuck a vein wrong and had to redraw.
Any way I insert the needle leaves a bruise. 
Or wrote a script wrong,
made the cough worse, in a way.
A doctor once said,
medicine has no room for error.
Which is another way I know 
​I'm out.