Allergy is a genetic trait where the immune system makes a mistake. It identifies a harmless substance like pollen as dangerous and tried to get rid of it with itching, sneezing, congestion and wheezing. It is possible to "reprogram" the immune response and to get rid of medicines. As an option to high dose nasal steroids and antihistamines, for some it is worth the hassle. It can be done in some cases with oral tablets rather than shots
The technique was discovered and has been refined over 100 years. It works, and is the standard everything else is compared to for safety, and sucess. There are two ways to deliver them now with new ways in the future
The FDA has recently approved oral tablets for imunization that are taken daily for three years. The tablets come for Ragweed and Grass only.
In Europe, this is the preferred method of vaccination.