  We study quantum corrections at one-loop order to the shear viscosity to
entropy ratio by implementing the Vilkovisky-Barvinsky effective action in
asymptotically Anti-de Sitter spacetimes. The shear viscosity is shown to
receive no corrections at this order, but the entropy acquires a logarithmic
correction. The coefficient of this logarithm turns out to depend on the spin
of the particles running in the loop and it can be either positive or negative.
On the basis of this result, we argue that the Kovtun-Son-Starinets bound
cannot be seen as a fundamental property of nature beyond the classical regime.
