Abstract: A process for manufacturing a vaccine, wherein the vaccine comprises diphtheria toxoid and tetanus toxoid and, and wherein the process comprises steps of combining (i) a first bulk comprising diphtheria toxoid and tetanus toxoid with (ii) a second bulk comprising tetanus toxoid but no diphtheria toxoid. This arrangement facilitates convenient manufacture of both pediatric and adolescent vaccines from the same bulks: the first bulk can have a diphtheriartetanus ratio that is suitable for pediatric vaccines, and the second bulk can be used to reduce the relative amount of diphtheria toxoid, as found in the adolescent vaccines.