Systems and Methods are disclosed for real-time decryption of a health registry-issued certificate for signaling a user vaccination and/or test status on a user device comprising the steps of: coupling a first user mobile device to a health registry for real-time decryption of a health registry-issued health certificate over a network; outputting on the first user mobile device at least one of an audible output, visual output, vibrational output, and/or textual output based on a pre-defined signaling protocol to signal a user vaccination status based on a token derived from the real-time decrypted health certificate; and decoding a device identifier/tag or token from the first user mobile device by a second user mobile device, fixed access device, or hand-held scanner, signaling to a second user a first user vaccination status based on a pre-defined signaling protocol and the tag/token.