In the first test they tested a BA.2.86 pseudovirus against the antibodies of pre-XBB blood donors and in the second test they tested it against antibodies from recent blood donors. While BA.2.86 is immune evasive, there was neutralization in the second test. That is suggestive that the new XBB.1.5 vaccines should provide some protection against it.
There's limited data on this variant, so it is too early to say much on it. This study while optimistic has a small sample size and pseudoviruses aren't always comparable to how the actual virus will behave.