The app spares people the tedious process of having to go to their local city hall to be issued a vaccine passport, but they must possess My Number identification cards to use it. Because only about 40 percent of the population currently has My Number cards, it is unclear how many people will download and use the app. The agency released the app for both iPhone and Android smartphones. Users need to download it through app stores and then enter a four-digit PIN number. When they present their My Number identification cards to confirm their identities, their smartphones will display their vaccine passports. Users can hide their QR codes, names or birthdates to protect their personal information. The government expects the smartphone-based vaccine passports to be used in its "vaccine-and-test package." That new effort is aimed at easing restrictions on eating and drinking establishments and event operators by requiring them to ensure that their customers are fully vaccinated or have tested negative for COVID-19. Smartphone vaccine passports can also be used as proof of full vaccination when traveling to more than 70 countries or regions, including the United States and South Korea.