The term "jab" to mean "vaccine" is common here in Australia, at least.
I am generally fine with needles, but I still have memories of getting a cat scan as a young teenager, where they had to inject some kind of fluid into my spinal column, preceded by the teeniest little needle you've ever seen to administer an anesthetic. It seemed to take them forever, and I was in tears. They admonished me thus:
"We had a little girl in here, and she didn't cry."
"I DON'T CARE"
I'd rather not go through that again, thank you.
I'll be getting flu jab in the near future. Some people have bruising and all kinds of horrible problems, but luckily for me, it is no problem, and the people who administer it are pretty skilled at it.