  We compute the one loop vacuum polarization from massless, minimally coupled
scalar QED in a locally de Sitter background. Gauge invariance is maintained
through the use of dimensional regularization, whereas conformal invariance is
explicitly broken by the scalar kinetic term as well as through the conformal
anomaly. A fully renormalized result is obtained. The one loop corrections to
the linearized, effective field equations do not vanish when evaluated
on-shell. In fact the on-shell one loop correction depends quadratically on the
inflationary scale factor, similar to a photon mass. The contribution from the
conformal anomaly is insignificant by comparison.
