An interesting tidbit I haven't seen being mentioned - there's a polio oral vaccine, and an injection, but while the oral drops are much cheaper (and have lesser side effects), there's also a small chance of actually passing the virus.
To clarify...you are referring to the method of vaccine administration not the type of vaccine.
Live attenuated viruses create viral shedding, which creates a chance of passing the virus and are administered using oral drops.
Inactivated virus vaccines, do not create viral shedding, cannot pass off the virus, and are administered using an injection.
In general, attenuated viruses have the potential to create viral shedding and by extension pass on an infection. The fact that the live attenuated polio vaccine is done via drops is a secondary design decision for , gut immunity, shelf stability, ease of administration, etc. That it is oral drops itself does not cause the chance of passing on the virus.
