However, the relegation-threatened club has so far been frustrated in its attempts to sign a central defender.
Sevilla have rejected a Newcastle bid for 28-year-old Diego Carlos, while Lille refused to sell Sven Botman, 22, earlier this month.
And the club, which is being quoted “inflated prices” in the wake of October’s takeover, is looking at “alternative targets”.
Speaking ahead of tomorrow’s game against Leeds United at Elland Road, Howe said: “We're looking at all alternative targets. Please don't think I'm sat there with a list of one player – and that's the only player that we would go for.
“We're looking at a huge list of names, but even when the list is big, it still doesn't mean that you're guaranteed to get one of those players over the line, because you've got to remember this is, in my opinion, the best league in the world.
"The number of players that can come in and make your team better makes it a very small pond that we're fishing in with the availability issues that we'll have in this window compared to the summer (due to Covid-19). I think that's what people have to understand."
Only Norwich City have conceded more goals than United this season, and the club is “working tirelessly” to strengthen the team, according to Howe.
Asked why the club hadn’t been able to sign a centre-half so far, Howe said: “This transfer window isn't as easy as people think.
"I understand the question, I get it. All I can assure you is that we're working tirelessly to improve the team in the areas that we need to.”
One issue is the prices that the club, which is now 80%-owned by Saudi Arabia’s Public Investment Fund following its £305million takeover, is being quoted for targets.
Howe said: “I think we are facing inflated prices because of January, and possibly also because of our name, but that’s something we have to deal with.”