Jayne Miller asks:

"A question for Paul Zimmer ; Considering all your information about the
immune system of a baby, and how human milk affects it, what about the
time schedual given for vaccinating babies for Polio, Tetenus etc. Should
thhis schedual be different for babies fed exclusively Human milk as
opposed to cows milk? Maybe start vaccinations at a later age? I would be
interested in any information about vaccinations and nursing babies."

Watching both this list and the parents-l, I've discovered that
immunizations
are a suprisingly contentious issue.  To try and avoid a "flame war,"  I'll

try to focus my reply on lactation and not on immunizations.

The ability of a child to produce ample amounts of antibody to a specific
immune system challenge (e.g. bacterial infection, immunizations, RSV,
etc.)
depends on the kind of challenge (i.e. polio vs. Hib vs. hookworm) and on
whether the child is breast or bottle-fed.  While we are only beginning to
look at the effects of human milk on infant immune system development, it
appears that breastfed infants have a maturational advantage in antibody
production in the first 2-3 months postpartum, but bottle-fed infants
rapidly
catch up and surpass them for several months afterwards.  This may be due
to
the breastfed baby being protected against challenges, through human milk
reducing the ability of the pathogen to bind to the infant's mucosa, while
the bottle-fed infant achieves immunity through infection and survival (I
always think of this as the russian-roulette approach to immune system
development).  Whether breastfeeding confers other advantages (e.g.
maturation of the immune system through growth factors in human milk or
anti-
idiotypic immunization of the child using the mother's antibodies) has not
been studied.

Given this current state of knowledge, we currently view breastfeeding as
more protective than preventative.  In other words, it seems to reduce the
odds that an infant will become exposed to a pathogen, but we do not have
much evidence that breastfeeding changes the course of the infection or
influences the child's innate susceptability.  Given the apparent advantage

that breastfed babies have in antibody production in the first few months,
one would think they would produce more protective antibody to an
immunization than their bottle-fed counterpart.  I've seen studies
discussing
these effects, but I can't seem to lay my hands on the folder with those
references (I've recently moved).  To consider a change in the vaccination
schedule based on current knowledge would be VERY premature.

I hope this helps.

Paul Zimmer, Ph.D.
Developmental and Clinical Immunology
University of Alabama at Birmingham

gham