Immunization Administration codes

For DC Medicaid, they will only pay for codes 90471,72,73 and 74. If the child receives oral/nasal flu vaccine and varivax, how should this be coded? Everything I have read says that 90471 and 90473 are initial codes and 90472 and 90474 are add-on codes. The flu vaccine would be 90473, but the varivax is IM. 90473 and 90472? Thanks! Linda