(left) Nuclear modification factors $R_{\rm pPb}$ and $R_{\rm PbPb}$ of electrons from beauty-hadron decays at mid-rapidity as a function of transverse momentum for minimum-bias p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV and 20% most central Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV. The data points of the p-Pb analysis were shifted by 0.05 GeV/$c$ to the left along the $p_{\rm T}$ axis for better visibility. (right) $R_{\rm PbPb}$ of electrons from beauty-hadron decays together with the corresponding result for beauty- and charm-hadron decays for the 20% most central Pb-Pb collisions. The vertical bars represent the statistical uncertainties, while the boxes indicate the systematic uncertainties. The normalisation uncertainties, common to all points, are shown as filled boxes at high $p_{\rm T}$ for all nuclear modification factors