We present LHCb results on quarkonia production in proton-lead collisions, using the data collected in 2016 at $\sqrt{s_{\mathrm{NN}}} = 8.16\,\mathrm{TeV}$. Measurements are performed in the high rapidity region (pseudo-rapidity between 2 and 5), covering both forward ($p$Pb configuration) and backward (Pb$p$ configuration) rapidities. Measurements for charmonium states include prompt and from-b-decay components which are disentangled. The large increase of the data sample, with respect to the $5.02\,\mathrm{TeV}$ sample collected in 2013, allows a remarkable improvement in the accuracy of the studies of nuclear matter effects.