  The level-$1$ integrable highest weight modules of $U_q(\widehat{sl}_2)$
admit a level-$0$ action of the same algebra. This action is defined using the
affine Hecke algebra and the basis of the level-$1$ module generated by
components of vertex operators. Each level-$1$ module is a direct sum of
finite-dimensional irreducible level-$0$ modules, whose highest weight vector
is expressed in terms of Macdonald polynomials. This decomposition leads to the
fermionic character formula for the level-$1$ modules.
