Ward has missed the Rams' last 11 matches since sustaining the problem during the 1-0 win over east midlands rivals Nottingham Forest at the City Ground at the end of September.
Manager Nigel Clough, whose side welcome Leeds on Saturday, is not putting a timescale on the Northern Ireland international's return.
He said: "We'll see how the hamstring settles down following the injection. It's just time and patience with Jamie.
"His chances of being ready for Saturday? It depends how the hamstring settles down this week."
- Sports & Recreation