Neutrino-photon reactions for energies above $m_e$

We show that neutrino-photon reactions above $m_e$ are dominated by the reaction $\nu \gamma \to \nu e^+ e^-$. We calculate its cross-section and see that it is larger by several orders of magnitude than the cross-sections of other neutrino-photon processes, for energies above $m_e$. We also discuss potential astrophysical and cosmological consequences.