Will you need a COVID-19 vaccine to cruise this year? With a growing number of cruise lines announcing plans to restart operations in the next few months, it’s become a pressing question for cruisers — and the answer isn’t always clear. In recent weeks, more than a dozen cruise lines have announced plans to require passengers to show proof of a COVID-19 vaccine before stepping aboard a vessel (including, over the weekend, Disney Cruise Line). At the same time, a few lines have said they would not require passengers to be vaccinated for COVID-19 — at least for now. But...