Which step of vaccine production ensures removal of all interfering material that may spoil the activity of vaccine?

Correct Answer: Purification
The production od vaccines is a long process as it requires 4 steps. Propagation, Isolation, Purification and Formulation out of which Purification method ensures removal of unnecessary materials which may further spoil the activity of vaccines. These materials may also cause side effects to humans, if vaccine is by chance licensed. Hence, this step is very important in order to purify it for future use and prevent any kind of damage.