Levende svækkede Newcastle disease-vacciner skal fremstilles af en Newcastle disease-virusstamme, hvor master seed er blevet testet og har vist at have et intracerebralt patogenicitetsindeks (ICPI) på:
Live attenuated Newcastle disease vaccines must be prepared from a Newcastle disease virus strain for which the master seed has been tested and shown to have an intracerebral pathogenicity index (ICPI) of: