Cosmological Constant Suppression in Non-Stationary Scalar Covariant State

We study a spatial-temporal structure of quantum fluctuations in the stress-energy tensor of zero-point modes for a scalar field in order to formulate a covariant model. The model describes an invariant vacuum contribution to the cosmological constant in the non-stationary coherent state in a finite volume. Bare and effective mean values of vacuum energy density are compared.