Lisa:  Your question about the possible allergy of a baby to the medium in
which the vaccine was grown and the preservatives is a good one.
Certainly in vaccines which were grown on egg medium, there is a potential
concern in a highly allergic baby.  However, we have to remember that the
two most common allergens in babies are cow's milk and soy protein, so if
a mother needs a vaccine, are we more likely to introduce allergies by
letting her continue to nurse with the incredibly small traces of a
substance which *may* cause an allergy, or by having her temporarily
interrupt breastfeeding and giving one of the two most common allergens
full strength?  Regards, Alicia Dermer, MD, IBCLC.