QR codes store exactly the information passed as input during their generation process. If you have a piece of paper with a printed QR code, it does not contain any additional information besides the data inputted for encoding. If you take a photo of a QR code using your smartphone, it may attach personal data to the photo itself, such as name, location, or any other information that can be derived from smartphone memory. Concerning personal vaccination passports/certificates, in some cases, QR codes may contain personal data that you might want to keep private. In general, such QR codes simply store links to external pages, and data on such pages are usually anonymized. To verify this, you may check information on the official website of your local authorities or control what exactly is encoded in your QR code using the Aspose.Barcode QR Code scanner.