  The influence on the fusion process of coupling transfer/breakup channels is
investigated for the medium weight $^{6,7}$Li+$^{59}$Co systems in the vicinity
of the Coulomb barrier. Coupling effects are discussed within a comparison of
predictions of the Continuum Discretized Coupled-Channels model. Applications
to $^{6}$He+$^{59}$Co induced by the borromean halo nucleus $^{6}$He are also
proposed.
