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.
Presumably the version they use in Star Trek avoids that problem somehow, so it’s still a thing that would need to be invented.
The doctors are constantly jabbing people one right after another and often through the uniform…I’d love to see the explanation in universe for that
Maybe their uniforms are self-sterilizing.
Medicine is improved so everyone has super immunity in the future. So it’s not that the hypo isn’t pushing dirt into their veins, it’s that they don’t care.