The Varicella-Zoster Virus (VZV) causes chickenpox and can reactivate years later as shingles (Herpes Zoster). Shingles presents as a painful, localized rash containing active VZV particles within the blisters. When an infant who has never had chickenpox or the vaccine is exposed to active shingles, the virus can transmit. The baby will not develop shingles; instead, they will contract their first VZV infection, which is chickenpox. This exposure requires immediate medical evaluation due to the potential for severe infection, especially in newborns.
How Shingles Transmission Occurs
Shingles is less contagious than chickenpox but is transmissible through direct contact with the rash. Transmission primarily occurs when a susceptible person, such as an infant, touches the fluid within the blisters before the lesions have fully crusted over. The infected person is contagious from the moment the blisters begin to weep until all lesions have completely dried and formed scabs.
Airborne transmission is also possible, though less common than direct contact, if the rash is extensive. Once the lesions are crusted and dry, shingles is no longer contagious, and the risk of viral spread ceases.
When an infant contracts VZV from a person with shingles, they develop the primary infection, which is chickenpox. An infant cannot get shingles directly because shingles results from VZV reactivating from a dormant state, which only occurs after a prior chickenpox infection.
The Clinical Outcome: Chickenpox in Infants
The clinical outcome for an infant exposed to VZV is heavily influenced by passively acquired maternal antibodies. If the mother has a history of chickenpox or vaccination, she transfers protective antibodies across the placenta, resulting in a milder infection for the infant. This protection typically lasts for the first few months of life.
The greatest risk for a severe outcome is during the first 28 days of life, known as neonatal varicella. If the mother contracts VZV shortly before birth (five days before to two days after delivery), the infant is at high risk of severe, disseminated disease. In this scenario, the infant is exposed to a high viral load without sufficient time to acquire the full protective benefit of transferred antibodies.
Neonatal varicella can be life-threatening, with potential complications including viral pneumonia, encephalitis, and hepatitis. Symptoms typically appear five to ten days after birth, starting with fever and the characteristic vesicular rash. For infants exposed after the neonatal period, or those whose mothers are immune, the infection is often less severe, resembling typical childhood chickenpox.
Specialized Treatment and Urgent Care Protocols
Following confirmed exposure to shingles, immediate consultation with a pediatrician is necessary to determine the appropriate post-exposure prophylaxis (PEP). PEP aims to prevent or lessen the severity of the developing infection. The decision to treat is based on the infant’s age, the mother’s VZV immunity status, health, and gestational age.
For infants at high risk of severe disease, the primary intervention is the administration of Varicella Zoster Immune Globulin (VZIG). VZIG is a blood product containing high levels of VZV-specific antibodies that provide passive, temporary immunity. To be most effective, VZIG should be given as soon as possible after exposure, ideally within 96 hours, though administration up to 10 days later is sometimes allowed.
Antiviral medication, such as Acyclovir, plays a role in both prophylaxis and treatment. For high-risk infants who develop symptoms, intravenous Acyclovir is typically initiated within 24 hours of rash onset to reduce the infection’s duration and severity. Oral Acyclovir may be prescribed for high-risk, exposed infants to be started around day seven post-exposure, which is when the virus is expected to begin replicating.
Protecting Infants from Future VZV Exposure
Caregivers must take proactive steps to prevent VZV transmission if someone in the household develops shingles. The most direct action is the strict isolation of the person with active shingles from the infant until the rash is completely dry and crusted. The person with shingles must keep all lesions fully covered with a bandage or clothing at all times to prevent accidental contact with the infant.
Rigorous hand hygiene is mandatory, especially after touching the rash area or changing bandages. These measures significantly reduce the risk of the infant coming into direct contact with infectious fluid.
For susceptible household contacts who are not infants, such as older children who have never had chickenpox, the Varicella vaccine can be used as post-exposure prophylaxis. The vaccine should be administered quickly after exposure to prevent or modify the infection. Minimizing VZV exposure through isolation and strict hygiene remains the most effective way to safeguard an infant.