What i don't understand is that after getting Covid, you are only immune for 8-20 weeks - a few public persons have already contracted Covid twice now illustrat

What i don't understand is that after getting Covid, you are only immune for 8-20 weeks - a few public persons have already contracted Covid twice now illustrating this. With this new variant, and the fact that we need some pretty incredible amount of people immune at once, maybe say 80%, wouldn't this mean that we need to be vaccinated 4-5 times a year? How is this feasible, even for the richest countries?