My son and his college roommate had TONS of problems trying to use the VeriFly app back in March when they were going from US to Canada on Spring Break. So, we didn't use it on our cruise in May 2022. As some others have posted, handed our boarding passes, passports and vaccination cards to Carnival host, our boarding passes were stamped and away we went. No need to use VeriFly. And this was all before the most recent lifting of restrictions. We cruise on Sept 17 and have no plans to use VeriFly. Will have our vaccine cards and passports with us. I assume it will go smoothly.