A construction of level 1 irreducible modules for $U_q(\hat{sp}_4)$   using level 2 intertwiners for $U_q(\hat{sl}_2)$
  We bosonize certain components of level $\ell$ $U_q(\hat{sl}_2)$-intertwiners of $(\ell + 1)$-dimensions. For $\ell = 2$, these intertwiners, after certain modification by bosonic vertex operators, are added to the algebra $U_q(\hat{sl}_2)$ at level 2 to construct all irreducible highest weight representations of level 1 for the quantum affine algebra $U_q(\hat{sp}_4)$. 
Boris Feigin, Jin Hong, Tetsuji Miwa