RELATED: If You Take Medication for This, You May Still Need a Mask, CDC Says. According to Fauci, there are three places he’s fairly confident will end up requiring people to be vaccinated to enter—colleges, airlines, and cruises. “You’re going to have at, a local, independent-level, things that the federal government is not going to be mandating,” but individual business still may, he explained. “There are organizations, particularly universities and colleges who are saying, notwithstanding what the federal government is requiring, if you want to come into campus and be in in-person learning, you’re going to have to show proof of vaccination,” the infectious disease expert said during the Bloomberg Businessweek conference on May 20, Business Insider reports. Multiple colleges—from Ivy League schools like Yale University and Columbia University to state schools like Rutgers University and the entire California State University system—have already announced that they will require students to be vaccinated if they plan on returning to campus in the fall, with more schools likely to follow in their footsteps. RELATED: For more up-to-date information, sign up for our daily newsletter. There’s a high probability cruise ships will be next, Fauci added. Currently, there is no vaccine mandate, but there are different guidelines depending on vaccination status. The Centers for Disease Control and Prevention (CDC) recently updated its guidelines to say that cruise lines no longer have to test fully vaccinated passengers before embarking on the trip or returning home. However, unvaccinated passengers must still be tested the day they board the ship, on the day they return to port, and between all back-to-back sailings. Additionally, if they come in contact with a positive COVID case, unvaccinated passengers must get tested and potentially quarantine for two weeks. To avoid the extra risk, cruise lines may ultimately only allow vaccinated passengers onboard. According to Fauci, some airlines will also probably begin mandating vaccines to fly with them. The CDC recently adjusted their mask guidelines for fully vaccinated people, allowing them to remove their masks in most places, aside from health care facilities, public transportation, and airports. On May 19, Fauci told Axios that the reason people can’t go maskless on a plane yet is because it’s hard to know who is vaccinated and who is not. “It’s complicated because the people who are vaccinated could easily be on airplanes without a mask because we know you’re protected, whether you’re indoor or outdoor,” he explained. “The trouble is that we don’t have vaccine passports, so we don’t know who is vaccinated or not.” Fauci said he had hope that in a couple of months, it may be a different story when it comes to domestic flights.ae0fcc31ae342fd3a1346ebb1f342fcb RELATED: Dr. Fauci Reveals the Key Difference With Vaccinated People Who Get COVID.