How?
Well for some it can be a literal bad experience with the object of fear - in this case, needles and medical procedures - but for most, it's a more general struggle to regulate anxiety, and the needle has become the focus of the anxiety.
It's also true that for some people anxiety can morph into angry or even aggressive resistance. Makes me wonder how many people who vehemently argue and fight against vaccinations are driven by trypanophobia?
So, what to do. There are three areas of focus - preparation, what to do when there and how to use rewards.
The most important part of preparation is to learn and practise some basic relaxation techniques. You can google them, but most focus on the breath and using the physiology of breathing to downregulate the nervous system. When we're anxious we tend to breathe shallowly, and this makes us feel more breathless and increases anxiety.
An easy breathing exercise to practise is to simply place your hand on the diaphragm, just below the rib cage, and make sure it moves when you breathe - this is called "belly breathing".
It can also be useful to prepare distractions, for the immediate wait beforehand, or even during the shot. Headphones with relaxing music, or engaging audiobooks or podcasts can be helpful, as can taking things to occupy your hands, fidget spinners, ice packs or crafts - knitting, for example, if that's your thing.
It's also fine to take a support person - although make sure you pick someone who helps keep you calm!
All the way through the process, but especially once you're there for your shot, be validating and kind to yourself. It's really normal to want to push ourselves, and in doing so give ourselves a hard time, that internal voice that tells us to just "harden up and get over it". However, when it comes to anxiety that simply doesn't work, as it winds us up.
It's okay to accept that it's awful, and do it anyway, and work at soothing ourselves like we might a child or a good friend who is scared or anxious.
When it comes to the injection itself - simple tip - don't look! And practise the relaxation exercises you have already learned.
Also make sure you allow yourself, and plan and look forward to a simple reward - maybe something small like a bag of favourite lollies (they give kids a lollipop after shots for a reason), a nice coffee, the rest of the day off work or a nice meal.
Ultimately, anxiety forces us to over-focus on ourselves and what is happening inside us. The reason we take the step of getting vaccinated is not just to protect ourselves, but because we're stronger together. We do it to protect each other, because we're part of a community - and meaning and sacrifice makes doing hard things, if not easier, then worth a little bit of pain.