In this research study the investigators want to learn more about an investigational medicine called VE416 in combination with vancomycin (an antibiotic) while undergoing peanut oral immunotherapy. VE416 is a combination of dormant (inactive) bacteria given in a capsule. The bacteria are reactivated once they reach participants intestines and in combination with peanut flour may help to prevent participants from getting sick (upset stomach, breathing problems, and skin problems) when participants come into contact with peanuts.
The investigators are doing this research study to find out if VE416 in combination with vancomycin (an antibiotic) while undergoing peanut oral immunotherapy can help people with peanut allergy. VE416 is a consortium of commensal, or "friendly", dormant (inactive) bacteria given in a capsule. The bacteria are reactivated once they reach participants intestines. The investigators also want to find out if VE416 with peanut oral immunotherapy is safe to take without causing too many side effects.