  The quantized Dirac field is known, by a result of Fewster and Verch, to
satisfy a Quantum Weak Energy Inequality (QWEI) on its averaged energy density
along time-like curves in arbitrary four-dimensional globally hyperbolic
spacetimes. However, this result does not provide an explicit form for the
bound. By adapting ideas from the earlier work, we give a simplified derivation
of a QWEI for the Dirac field leading to an explicit bound. The bound
simplifies further in the case of static curves in static spacetimes, and, in
particular, coincides with a result of Fewster and Mistry in four-dimensional
Minkowski spacetime. We also show that our QWEI is compatible with local
covariance and derive a simple consequence.
