Way too late to prevent the mother from getting the virus, whether it's
Herpes or one of the several Coxsackie viruses which can cause similar
lesions in the baby's mouth.  Once the baby has the sores in her mouth,
she's got the infection.

This does not mean she will develop sores.  If we are fairly sure that
it is Herpes (scraping from mouth examined under electron microscope
will confirm the diagnosis), she could be treated with acyclovir and she
should continue breastfeeding.  If she develops the lesions, she could
still be treated with acyclovir and continue breastfeeding.

Jack Newman, MD, FRCPC