A Doctor's Office Has Run Out of the Latest Flu

Multiple Choice

A doctor's office has run out of the latest flu vaccine,but many patients are asking for it.One of the nurses finds some vials from last year's batch in a refrigerator.Should they be used?

A) Yes,because the preservatives and refrigeration ensure that the vaccine is still fresh.
B) No,because each year the technology to make a good vaccine improves.
C) No,because each year the vaccine is made against different subtypes of the flu virus.
D) Maybe - the vaccine should be mixed in a test tube with the virus to see if it still inactivates it.