Rotaretilbo:

The Elites only lost eighteen destroyers, two cruisers, and one carrier when Joyous Exultation was destroyed. They still have quite a fleet to wield. Voro's fleet may be gone, but we can assume there are many other ships, like the battlegroup around Delta Halo. The Brutes were completely eliminated from around Delta Halo, which is where High Charity, and thus a large Covenant fleet of both Brute and Elite ships was parked.