We built a vaccination registry that is stored on the blockchain. We utilized Tierion's proof-engine for our hashing and data retrieval. The data stored on the blockchain is only accessible to the patient or whoever the patient gives permission to with their unique, secure key. The idea is that this is one module in a suite of modules that a health system can use in conjunction with a patient "wallet". First, we have VacVerify, next could be LabVerify or MedVerify, and all of that data can be stored and retrieved securely from the blockchain anywhere and at any time. We are building patient records for the future of healthcare.