I understand your concern about Shingles and possible transmission. Shingles develops form the same virus that causes Chickenpox which is the Varicella Zoster virus, and might develop in any people who have had chicken pox in the past.
Let me reassure you that usually shingles develops in adults after the virus stays dormant in the body for years, a person with shingles could only transmit chicken pox and NOT shingles. In my opinion, your son might have probably acquired chicken pox due to direct contact with your fiancée. It is not dangerous for him to be in contact now. It’s important that your fiancée seeks medical counseling right away to begin anti viral medications within a few days of a shingles outbreak for best results. When taken as directed, these drugs should be safe during pregnancy.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.