GLOBAL DTP MANUFACTURING CAPACITY AND CAPABILITY - STATUS-REPORT - JANUARY 1995

A recently completed survey of 63 manufacturers of diphtheria-tetanus- pertussis (DTP) vaccine and its components in 42 countries shows that there is potentially a large excess installed capacity for DTP product ion. However, many manufacturers ave not producing to capacity, and de mand and supply for this vaccine are not matched in individual countri es, About half of all countries producing DTP vaccine and its componen ts do not have fully functional national control systems, and some cou ntries are performing none of the critical functions for an effective control of quality. Thus, potential for export of excess capacity is l imited. The data collected indicate much homogeneity in the preparatio n of diphtheria and tetanus toxoids. Nearly all manufacturers use the same seeds and similar purification methods, but there is variability in whether purification is done before or after conversion of toxin to toroid, About 10% of all manufacturers do not meet WHO-defined standa rds of purity for these toroids. There is much move heterogeneity in t he pertussis seed strains and the methods of purification used. The fo rmulation of DTP vaccine differs considerably among producers. Potency testing is not being done by the WHO-recommended method by about 50% of manufacturers on lots of diphtheria and tetanus toxoids for release . Testing of irreversibility of conversion of toxin to toroid, a WHO-s pecified safety test, is also not being clone on each lot of diphtheri a toroid by 15% of manufacturers surveyed nor on each lot of tetanus t oroid vaccine by 30% of manufacturers surveyed. Access to technology t o develop new DTP-based combination vaccines will be delayed if these manufacturers cannot ensure consistent high quality vaccine for their target populations. The results and conclusions suggest areas for futu re activities to strengthen the supply and quality of DTP and DTP-base d combination vaccines. Copyright (C) 1996 Elsevier Science Ltd.