Does anyone know why vaccines are injections only, the exception I know of being polio?
Just had a morning thought; why aren't vaccines offered through other delivery methods like nasal sprays, pills and patches? Is it economics/ manufacturing issues? Or perhaps injections are the most effective?
I dunno, why I'm asking.
Most vaccines are injected into the deltoid muscle to optimise the immunogenicity of the vaccine and to minimise adverse reactions at the injection site. The intramuscular route is by far the most effective, an alternative to the deltoid muscle is the anterolateral aspect of the thigh.
So much time looking for the actual injection site and all I needed was to view other's comments. One good thing is that I learned something not too pleasant. [sciencefocus.com]
That was good. It also depends on the type of vehicle for transfer. Sugar may not serve will as a fake protein to get into our body
Most vaccines would get destroyed by your stomach juices. I have to inject insulin for the same reason.
@powder The size and solubility of the agent can prevent it from penetrating the skin with a patch. Old school killed and attenuated virus vaccines would be very challenging to administer through patch. I am assuming, without much actual knowledge, that RNA vaccines like for the new covid would be much smaller than a virus and so maybe we'll see them.
@powder That's if it can be absorbed through the skin. Injection is 100% immediately into the blood stream if into a vein or if in muscle/fat, it's quickly into the blood stream. Some particles do not transfer through skin well and the dosage is more assured with injection. (my brother is a pharmacist, this isn't my knowledge!)
It depends on best absorption and where the best absorption is. I have to inject B-12 once a week. Most people can absorb that through the digestive tract. My body won't. Injection is a sure fire way to get it into the body, other methods aren't as guaranteed. Depending on what the person has eaten, etc.
Polio and other organisms that can infect through the digestive tract are good candidates for oral vaccines. Respiratory viruses and others that infect through blood and mucus are too fragile for that route. There are nasal flu vaccines. Your respiratory and digestive systems are evolved to protect you; the injection bypasses much of your passive immune defense.
It's just a guess, but...
I should think that the most effective way to get something into the bloodstream (where the white blood cells are) would be by venipuncture. But this is more difficult, so the second-best way is by random injection somewhere on your body.
My kiddo did have a couple of innoculations by nasal spray. This was probably less effective, but still good enough.
Again, just a guess. I'm better at drawing blood than I am at putting stuff into it.
@powder hopefully you'll get some more informed answers.