Shingles are infective only by direct contact.  If the baby does not get
into direct contact with the lesions, he cannot get infected.

What if he does?  Shingles occurs only when you have had previous
chicken pox, which means the mother undoubtedly has high antibody
titers, especially now that she has a new infection, which would raise
her antibody titers, and possibly increase anti infective factors in her
milk.

The baby is protected as well by placentally transmitted antibodies.

Jack Newman, MD, FRCPC