Your medical information is invaluable to emergency responders and can mean the difference between life and death. EMTs, doctors and nurses need to know things like what medications you might be allergic to, what medical conditions you have, what medications you are taking, what blood type you are and so on, so that they can provide the best treatment as quickly as possible. To this end, Apple has included the ability to automatically share your health information when you make an emergency call in iOS 13.5.
Like the Apple Watch SOS feature introduced with watchOS 3, iOS 11 gives your iPhone a shortcut that automatically calls the local emergency services (like 911) and your emergency contacts when invoked. Hopefully you will never have to use it, but if you ever find yourself in dire straits it could prove to be a lifesaver. Once you have it set up, Emergency SOS allows you to push the sleep/wake button rapidly five times, at which point it makes the call.