Vaccines can be delivered through the skin using ultrasound. This method doesn’t damage the skin and eliminates the need for painful needles. To create a needle-free vaccine, Darcy Dunn-Lawless at the University of Oxford and his colleagues mixed vaccine molecules with tiny, cup-shaped proteins. They then applied liquid mixture to the skin of mice and exposed it to ultrasound – like that used for sonograms – for about a minute and a half.
That tracks with my experience. I’m shot-tolerant, so I have the calmness to observe. Of course, some are also just inherently more irritating/painful than others, and there’s different volumes of liquid as well.
For instance, if you’re shot-averse, get Pfizer Covid rather than Moderna Covid. It’s ⅓ of the size/dose.