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Transplacental immunity to varicella-zoster virus in extremely low birthweight infants
D B Mendez1, M B Sinclair, S Garcia
1Department of Pediatrics, Wyler Children's Hospital, University of Chicago, Illinois.
Insights
Extremely premature infants may possess protective antibodies against chickenpox (varicella-zoster virus). This study found that most infants in intensive care had sufficient varicella-zoster virus antibody levels, suggesting passive immunity transfer.
Area of Science:
- Neonatalogy
- Immunology
- Infectious Diseases
Background:
- Infants in intensive care nurseries (ICN) face unique health risks.
- Exposure to chickenpox (varicella-zoster virus, VZV) in premature infants is a concern due to potential lack of transplacental antibody transfer.
- Premature infants, especially those with low birthweights or early gestational ages, are particularly vulnerable.
Purpose of the Study:
- To investigate the presence and levels of VZV antibodies in premature infants following inadvertent exposure.
- To determine if passive immunity to VZV is effectively transferred to extremely premature neonates.
- To assess the risk of VZV infection in this vulnerable population.
Main Methods:
- Serum samples were collected from 16 infants in an ICN after exposure to an adult with chickenpox.
- Indirect fluorescent antibody testing was used to detect and quantify VZV antibody levels.
- Infants were categorized by birthweight (≤1000 gm) and gestational age (≤28 weeks).
Main Results:
- Fourteen out of 16 infants demonstrated VZV antibody levels of 1:16 or higher.
- Six of eight infants weighing ≤1000 gm had adequate antibody levels.
- Eight of ten infants with gestational ages ≤28 weeks possessed sufficient VZV antibodies.
Conclusions:
- Passive transfer of immunity to VZV is common even in very premature infants (24-28 weeks' gestation).
- This suggests that extremely premature neonates may have a degree of protection against VZV infection.
- Further research may explore the clinical implications of this passive immunity in neonatal intensive care settings.
Abstract:
Sixteen infants in our intensive care nursery (ICN) were inadvertently exposed to an adult who presented the next day with chickenpox. Since a majority of the patients were extremely premature, we were concerned that they might not have received transplacental varicella-zoster virus (VZV) antibody, and consequently would be at risk for contracting chickenpox. Serum samples were obtained from each infant and examined for the presence or absence of VZV antibody. Fourteen of the 16 infants had antibody levels equal to or in excess of 1:16 by indirect fluorescent antibody, including six of eight infants with birthweights equal to or less than 1000 gm, and eight of ten infants with gestational ages equal to or less than 28 weeks. Passive transfer of immunity to VZV appears to be common in infants as young as 24 to 28 weeks' gestation.