The funny part is that I just posted that Carnival requires vaccination for adults and masks -- and will demand all sailings have a 95% vaccination threshold. He better go read their policy carefully for whatever cruise line he is taking. The few unvaccinated on board Carnival (mainly children) are segregated, not allowed in most venues, and must dine in their own special section. Same on just about every other cruise line. The top-end elite cruise lines are rejecting unvaccinated bookings. The only market where unvaccinated cruisers are being accepted are the low end, small ship cruise lines -- which are evading CDC requirements due to their small size.