Chickenpox, caused by the varicella-zoster virus, is a common childhood illness. New parents often wonder about the risk this infection poses to their newborn. While generally mild in older children, chickenpox can present a more serious concern for infants. This article will clarify how newborns can contract chickenpox and the factors influencing their susceptibility.
How Newborns Acquire Immunity
Newborns typically receive initial protection against chickenpox through passive immunity. This occurs when a mother, who has previously had chickenpox or been vaccinated against it, transfers protective antibodies to her baby across the placenta during pregnancy. These maternal antibodies offer temporary defense against the varicella-zoster virus during the first few weeks to months of life. The level of protection provided depends on the mother’s antibody levels.
This passive immunity is not permanent, and its effectiveness diminishes over time. Studies indicate that antibodies protecting against varicella can fade quickly, with many infants becoming susceptible to infection within a few months.
When Newborns Are Susceptible
Newborns can contract chickenpox under several specific circumstances, particularly when maternal immunity is absent or insufficient. If a mother has never had chickenpox or has not been vaccinated, she cannot pass on protective antibodies to her baby, leaving the newborn vulnerable.
Another scenario involves maternal infection during pregnancy, though the risk of serious complications for the baby varies depending on the timing. If a pregnant mother contracts chickenpox during the first 20 weeks of gestation, there is a small chance (around 1-2%) that the baby could develop congenital varicella syndrome. This rare condition can lead to birth defects affecting various body parts due to transplacental transmission of the virus.
The highest risk for severe neonatal chickenpox occurs if the mother develops symptoms of the infection shortly before or after delivery. This period is generally defined as 5 days before to 2 days after birth. During this time, the baby is exposed to the virus but does not receive enough maternal antibodies in time for protection. This can result in a severe form of the disease known as neonatal varicella.
Newborns can also contract chickenpox through postnatal exposure from infected individuals, even if the mother is immune. If a family member or caregiver has chickenpox, the virus can spread through respiratory droplets or direct contact with blisters. While maternal antibodies offer some protection, direct exposure can still lead to infection in the newborn.
Signs and Severity in Newborns
Chickenpox in newborns appears as a characteristic rash, often preceded by general signs of illness. Initial symptoms can include a fever, loss of appetite, irritability, and appearing generally unwell. These early signs may last for a day or two before the distinctive rash appears.
The rash begins as small red spots that quickly evolve into fluid-filled blisters, which then crust over. These lesions can appear on the face, chest, or abdomen and spread across the body, sometimes including sensitive areas like the mouth. New spots can emerge while older ones are healing, leading to rashes at different stages.
Newborns, especially those with limited or no maternal antibody protection, are at a higher risk for severe and widespread disease compared to older children. Their developing immune systems may struggle to contain the infection, leading to more serious outcomes. Complications can include bacterial skin infections, pneumonia, or inflammation of the brain (encephalitis), as well as dehydration or Reye’s syndrome.
Prevention and Management
Preventing chickenpox in newborns involves strategies focused on maternal immunity and minimizing exposure. Women planning pregnancy who are not immune to chickenpox should consider getting vaccinated before conception. The chickenpox vaccine is effective.
Avoiding contact with anyone who has chickenpox or shingles is important for non-immune mothers and newborns. The virus is contagious and spreads through close contact. General hygiene practices, such as frequent handwashing for all family members, can also help reduce transmission risk. Limiting visitors, particularly those who may be unwell or unvaccinated, during the newborn period can further protect the infant. Vaccinating other household members is also important, as babies cannot receive the vaccine until they are at least 12 months old.
If a newborn is exposed to chickenpox or shows symptoms, immediate medical consultation is advised. In high-risk situations, such as when the mother develops chickenpox around the time of delivery, a specific treatment called Varicella-Zoster Immune Globulin (VZIG) may be given. VZIG provides immediate, temporary passive immunity to the newborn, which can help reduce the severity of the infection.
Antiviral medications, such as acyclovir, may be prescribed if the newborn develops the infection. Acyclovir can help relieve symptoms and accelerate healing. Supportive care measures, like ensuring adequate fluid intake to prevent dehydration and applying calamine lotion for itching, are also part of management. Severe cases of neonatal chickenpox may require hospitalization for close monitoring and treatment.