Simon Grayson says James Vaughan was battling a sickness bug as he landed his first Black Cats goal.
The striker converted an excellent cross from Callum McManaman to end his drought, particularly important as Lewis Grabban faces a prolonged spell on the sidelines.
Grayson said: "Vaughan was in bed all day Thursday and Friday with sickness and diarrhoea so he was on his last legs the last 20 minutes.
"Lewis going to be out for a few weeks. I won’t say how long but it is weeks rather than days, it’s a blow to us because he’s doing well.
"That’s why Vaughany did so well to get off his sick bed and contribute, I’m really pleased for him, he played and got his rewards with the goal. Its not an area of the pitch where we’ve got a lot of bodies at the moment but Duncan’s played today, got a penalty and scored it which is pleasing."
Hull City's late equaliser leaves Sunderland hovering above the relegation places with six points but Grayson said his side took an important step by stopping their run of consecutive defeats.
A trip to Everton in the Carabao Cup this week is followed by league games against Cardiff City, Ipswich Town and Preston North End before the next international break.
Grayson said: "We were organised and had to be, against a side who have a good record here and have scored a lot of goals here. We limited them to few opportunities and we countered against them quickly, we kept the ball and had sustained pressure at times, it was pleasing to build on the performance from the other night.
"We could have crumbled and lost the game but we had to do whatever was required to stop the cycle of four straight defeats and a point is a start against a good team."