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.
A machine that produces ultrasonic waves is not that complex. It’s the sensors and qualified technician to read and capture the scans that’s expensive.
Plus have you ever had to physically restrain your child through a needle shot? You said “easiest” and that shit ain’t easy.
You seem to be the only commenter here who recognizes that this would be amazing for pediatric patients - who coincidentally receive way more vaccines than adults.