The invention provides a process for producing a combined vaccine containing an inactivated Sabin strain of poliovirus, a Bordetella pertussis protective antigen, a diphtheria toxoid and a tetanus toxoid, the process including a step of producing a high-titer Sabin strain poliovirus. The inventive process for producing a combined vaccine, including a step of culturing, in the presence of from about 4 g/L to about 6 g/L of a microcarrier, Vero cells to be inoculated with a Sabin strain of poliovirus, is useful as a process for efficiently producing a combined vaccine containing an inactivated Sabin strain of poliovirus.
