  The thermal contribution to the chiral vortical effect is believed to be
related to the axial anomaly in external gravitational fields. We use the
universality of the spin-gravity interaction to extend this idea to a wider set
of phenomena. We consider the Kubo formula at weak coupling for the spin
current of a vector field and derive a novel anomalous effect caused by the
medium rotation: the chiral vortical effect for bosons. The effect consists in
a spin current of vector bosons along the angular velocity of the medium. We
argue that it has the same anomalous nature as in the fermionic case and show
that this effect provides a mechanism for helicity transfer, from flow helicity
to magnetic helicity.
