Chickenpox is generally only a severe problem if caught by the mother within
a few days of delivery and by the infant just after delivery.  A 10 month old
can generally handle chickenpox just fine.  The mom has a greater potential
for getting significantly ill, as chickenpox is worse in adults than in kids.
 Relatively few adults have not had chickenpox--is the mom sure she never had
it?

There is a chickenpox vaccine out now.  Although it has not specifically been
tested to see if giving it close to varicella exposure would prevent or
lessen the severity of wild chickenpox, it might be worth a try.  The RED
BOOK published by the AAP says "The currently formulated vaccine is not
currently recommended for preventing the occurence of varicella following
exposure to varicella or zoster.  However, studies with earlier product
formulations indicate that the vaccine given within three days of exposure
may prevent subsequent clinical illness in the contact.  While postexposure
prophylaxis is not an FDA-approved indication for varicella vaccine, its use
for this purpose may be effective and confers little risk.  If vaccine is
given follwoing exposure, parents should be informed regarding the
possibility of chickenpox occurring in spite of vaccination."

Generally Varicella IG is only recommended for administration to people who
are immunodeficient, as it is quite expensive and rare.  The mom might
consider using acyclovir to decrease the severity of the varicella should she
start breaking out with it.  (But giving acyclovir in advance to prevent
occurrance is NOT recommended).

I would encourage any adult who has never had chickenpox to get themselves
immunized.  It's a two-dose regimen for adults.  Our office is routinely
immunizing the 12-15 month olds with varicella vaccine, plus giving it to any
older child who has never had varicella.

Varicella vaccine should be quite safe to give to a breastfeeding mom.

Linda L. Shaw MD