All three have potential problems. Clear is the only service we tested that works as well on Android phones as it does on iPhones. It is difficult to know where the tests of these applications will be accepted. VaxYes, which says it has more than 1 million users, told us that it is targeting states like Kansas, Texas and South Carolina. And while the health of Clear and Airside passes it should Pass the meeting anywhere your paper card does, acceptance still depends on each destination.