You can use your iPhone to scan in your vaccination card and then create a Shortcut to display it with one tap. This can come in handy when it isn't convenient to carry your card with you.
Update for iOS 15: You need to use the Get File From Folder action. Set the Folder to the folder where the file is located, such as Shortcuts if you put it in there. Then set the file name to the exact filename. Remember to check the info on the file to make sure you know it exactly. For instance, it is easy to set the name to Vax.jpg and then inadvertently end up with the file name Vax.jpg.jpg. Here is a look at what an iOS 15 Shortcut may look like.