The Saints have struggled with injuries this season, but are boosted by the news that Kyle Walker-Peters is fit.
Asked if they need a signing in that area by reporters, Hasenhuttl told the Daily Echo: "Yeah, this is no surprise that we tried it, yeah?
"I mean, we tried everything but it wasn't possible in the winter, because of the special situation every club was in.
"With COVID and everything, nobody wanted to loan players because nobody knew how we were at that moment, with the situation where numbers were rising – we had big problems with COVID cases in the league.
"We tried everything but it didn't work.
"Finally, we know that we have to do something there in the summer - and therefore we have to concentrate now."