zoereid asked: A woman who has offered to be a wet nurse is concerned that she might get infected from nursing a child who is sick. She was specifically concerned about a child recently vaccinated (she does not vaccinates her own children). Is there any validity to that concern?

Having given a brief glance at the history of wet-nursing, I would guess (although I am not certain) that any increased risk of infection specifically from nursing a child who is sick is relatively low (over and above just being around such a child). From my readings on vaccination, I strongly doubt the child being vaccinated will create further risk outside that which the sickness itself creates. As far as I am aware, there is no good evidence to support the kind of thinking that suggests otherwise (in terms of the vaccination concern).

I strongly recommend the book, Bad Science, by Ben Goldacre as well as his and Orac’s blogs for evidence-based sources of information about such topics.