That will never happen, just like it will never happen on land. It is a virus and should be treated like every other virus. I was unvaccinated until a month ago and never (as far as I know and was tested for work for months) got covid. I went back to almost normal life last year too. If you are worried about getting any type of virus, I would say don't go to public places where there are a lot of people. Otherwise, the rest of us are not worried and want to start getting back to almost 100% normality. Cruises are the only place that most of us need to test and vaccine.