In a past post relating to immunizations someone mention having no responce
to several doses of MMR vaccine. Sorry I forgot who.
Anyway I sent this question to the CDC'c immunization program. (
[log in to unmask]  they will take questions from anyone as long as theyre
immunization related.)
With permission from a net mom to post, here is a
paraphased summery of their responce:
First determine if the person is immune to rubella and mumps
as not responding to all 3 would be very unusual and
could indicate a problem with the vaccine such as being left
out too long.
Next send serum to a reference lab for a "plaque
reduction neutralizing test" to rule out false negative from
previous tests.
If not immune it is questionable what the effect from
additional doses would be, no good data on this. Responce
rate to first dose of MMR is 95%. When the second dose is
given 95% of the previous 5% of nonresponders will respond
to give an overall coverage >99%. therefore this person would
get protection from "herd immunity".
-Rob