I don't think talk of blood donation is going to help anyone struggling with a phobia of needles
Let's remind people that the needles used for vaccination are the smallest, thinnest sort, and you really do not feel anything much at all with them.
That's almost certainly true now
, but it wasn't so in my more tender years - unless I'm misremembering.
When I had my BCG, back in my early teens (1960s: I think all kids were given it, back then), I distinctly remember asking the nurse - who was a strictly no-nonsense sort of person - "will it hurt?". She laughed and replied "of course not - no worse than a bee-sting". Well, I've been stung by bees and wasps a few times in my life, and I assure you it does
hurt. And so did that jab - this is not something I'm likely to have forgotten - not even after all these years...
So things are definitely a lot more comfortable for would-be jabbees, nowadays!
As to needle-phobia - yes, it does exist, and yes it is as irrational as any other phobia. Think of spiders. Almost all spiders we encounter in Britain are totally harmless - but there are many folks who flee shrieking when they meet up with our eight-legged friend in the bath. And plenty of people cannot bear
to pick one up in the hand. Indeed, I've been told off for posting a spider photo on a forum without warning!
I doubt if any amount of reassurance that present-day vaccinations are completely painless, will overcome all these phobias...