  The effect of interactions on a system of fermions that are in a
non-equilibrium steady state due to a quantum quench is studied employing the
random-phase-approximation (RPA). As a result of the quench, the distribution
function of the fermions is highly broadened. This gives rise to an enhanced
particle-hole spectrum and over-damped collective modes for attractive
interactions between fermions. On the other hand, for repulsive interactions,
an undamped mode above the particle-hole continuum survives. The sensitivity of
the result on the nature of the non-equilibrium steady state is explored by
also considering a quench that produces a current carrying steady-state.
