That's generally how coronavirus vaccines work - you get antibodies for awhile, but you need to re-up again when the season comes around again.
With this one, hopefully we can put a good-sized dent in the infection rate due to the fact that vaccines will be coming out in waves concurrently with social-distancing and masks policies still in effect. The 2 combined should make a considerable difference for us.
Also worth noting: Even if your antibodies have faded, once this coronavirus is no longer "novel" to your immune system (i.e., once you've had it before), the impact of a subsequent infection will be a lot milder for your body.