None of those players who missed the 2-0 win over Luton Town last time out are in contention for a return to action this weekend, with the Blades also reluctant to sanction any further departures before Monday’s transfer deadline.
On Thursday Regan Slater became the fourth player to leave Bramall Lane this month when he completed a permanent transfer to Hull City for an undisclosed fee.
On the possibility of more exits, Heckingbottom said: “We have still got quite a lot of attacking options but at the minute we only had 16 outfield players fit and available today.
"We don’t want to leave ourselves short. If we’re not going to bring players in we need to make sure we’ve got enough numbers training, enough quality in the building.
"At any point, with injuries and illnesses, we could be leaving ourselves really short.”
Morgan Gibbs-White, Ben Davies, Luke Freeman and Enda Stevens are all ‘getting close to coming back’, Heckingbottom added.
He said: "They are all similar timescales now in terms of (sic) last couple of weeks.
“I’m hoping to get them all back in, all competing.
“Ben trained today – not all of the session – it’s his first day back in with the group after Covid.
“Hopefully we can keep progressing him. He worked hard in the couple of weeks before he had Covid and then he suffered with it.
"He had quite a few symptoms but he’s over it now an pushing on again.”