P2.M258: Transmission of vaccine-strain varicella zoster virus from an immunocompetent mother to an infant causing disseminated varicella

Introduction: Varicella is a highly transmissible disease caused by the varicella zoster virus (VZV). The incidence of varicella has dropped significantly since the development of the live-attenuated vaccine. However, there remains a hypothetical risk of transmission of vaccine-strain varicella zoster virus (Oka strain; vOka) to close contacts in the event of a localized eruption after vaccination. The risk of secondary disseminated varicella after such a transmission is even more rare. We report herein a case of transmission of disseminated vaccine-strain varicella from a mother to her 31-day-old infant after having received the varicella vaccine on postpartum day 1.

Case Description: A 31-day-old male presented to the emergency department with worsening jaundice and rash for 5 days. Physical exam revealed a vigorous infant with full body jaundice, scleral icterus, and a scattered maculopapular and vesicular rash involving most of his body. Laboratory testing revealed transaminitis and indirect hyperbilirubinemia with otherwise intact liver function. The patient was admitted to the acute care floor for further workup and management.
It was discovered that the mother had received the live-attenuated VZV vaccine on patient’s day of life 1, and developed a vesicular rash on her chest roughly two weeks after vaccination but continued to breastfeed the patient. The infant had no other sick contacts and no other reasonable exposures after delivery.
A swab was sent from a deroofed skin lesion and found to be positive for VZV DNA via polymerase chain reaction. The infant was initiated on acyclovir 60 mg/kg/day IV divided every 8 hours. The infant’s liver function was shown to be improving throughout his hospitalization. After 5 days, his lesions had crusted over, without development of new lesions. He was discharged home with oral acyclovir solution at a dose of 20 mg/kg every 6 hours to complete a 7-day course. The patient was seen by his pediatrician five weeks after admission and found to have completely resolved rash, and improvement of his transaminitis and jaundice.

Discussion: Disseminated Oka strain varicella after exposure to a vaccinated individual is an exceedingly rare phenomenon in infants, but one with important clinical significance. To our knowledge, this is the fourth case reported, and the third in the past two years. Our case adds to the growing body of literature, and is the first to show an infant with demonstrated liver injury secondary to neonatal disseminated varicella associated with postpartum varicella vaccination. As with other reported cases, the patient had an uncomplicated course and showed resolution of symptoms with administration of acyclovir.

Conclusion: Vaccine-strain varicella can be transmitted from immunocompetent individuals to otherwise healthy newborns, and cause disseminated disease with liver involvement. Systemic acyclovir was an effective treatment in our case and led to an uncomplicated course.