Repeat infection among unvaccinated is common. Practice safe behavior regardless of immunity levels. Best defense against any virus is staying strong & healthy with good nutrition and regular exercise. The regular exercise is keeping from getting any sickness, not even common cold for as long as I can remember, may be 20 years. By the way I am vaccinated because I love cruises, and done 5 since Sept 2021 and 3 more coming up in 2022.