Vaccines via needles but they aren't always via needles. Before that you basically just ate part of something infected, then you'd only get the disease a little which resulted in you surviving and being immune. It would always be watered down, like a skin flake diluted several times. Over time you'd eat many of them to build an immunity. These were the precursor to the modern vaccines.
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease.
the definition doesn't even require the use of a needle.
https://en.wikipedia.org/wiki/Vaccine
Vaccines via needles but they aren't always via needles. Before that you basically just ate part of something infected, then you'd only get the disease a little which resulted in you surviving and being immune. It would always be watered down, like a skin flake diluted several times. Over time you'd eat many of them to build an immunity. These were the precursor to the modern vaccines.
the definition doesn't even require the use of a needle.