2479. Varicella Zoster Immune Globulin Is Effective up to 10 Days Following Varicella Exposure in Pregnant Women, Immunocompromised Patients, and Infants: Results from a Large, Open-Label Expanded-Access Program
Session: Poster Abstract Session: Vaccines for Herpes Zoster Virus
Saturday, October 6, 2018
Room: S Poster Hall
Background: There are more than 300,000 cases of varicella annually; nonimmune individuals exposed to varicella-zoster (VZ) virus have a high likelihood of developing varicella. VZ immune globulin (VARIZIG®) is used for postexposure prophylaxis to prevent or attenuate VZ infection in high-risk individuals. We assessed varicella incidence and severity in high-risk subjects after administration of VZ immune globulin.

Methods: This open-label expanded-access program provided VZ immune globulin to physician-identified, high-risk subjects exposed to varicella. Subjects included immunocompromised children/adults, infants (including preterm infants, newborns whose mothers had VZ infection <5 days before or <2 days after delivery, and infants <1 year of age), and pregnant women. VZ immune globulin (125 IU/10 kg [up to 625 IU]) was administered intramuscularly, ideally ≤96 hours, but up to 10 days, postexposure. Incidence of varicella rash and severity (>100 pox, pneumonia, encephalitis) were assessed up to 42 days after administration.

Results: The efficacy population (n = 505) included 263 immunocompromised subjects (32 adults, 231 pediatric), 137 pregnant women, and 105 infants. More than 97% of exposures fit the CDC definition. Varicella incidence was low in immunocompromised subjects (4.5%, n = 12/269), pregnant women (7.3%, n = 10/137), and infants (11.4%, n = 12/105) and was similar when comparing administration ≤ 96 hours vs up to 10 days postexposure (6.2% vs 9.4%, respectively). Of 34 subjects with varicella, 54% were exposed in the household; 5 were considered severe. Common adverse events were pyrexia (4%), neutropenia (3%), and headache (3%). There were no product-related deaths and only 1 serious adverse event (serum sickness) considered probably related to VZ immune globulin.

Conclusion: Postexposure administration of VZ immune globulin resulted in low rates of varicella in high-risk subjects, regardless of administration timing within 10 days postexposure. VZ immune globulin—which is FDA-approved, recommended by the CDC, and widely available—was well tolerated and safe in high-risk subjects.

Myron Levin, MD, FIDSA, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, Jennifer Duchon, MDCM, MPH, Tufts Floating Hospital for Children, Boston, MA and Geeta K. Swamy, MD, Duke University, Durham, NC

Disclosures:

M. Levin, Merck: Consultant and Scientific Advisor , Consulting fee and Research support . GlaxoSmithKline: Consultant and Scientific Advisor , Consulting fee and Research support . Saol Therapeutics: Consultant and Scientific Advisor , Consulting fee .

J. Duchon, Saol Therapeutics: Consultant and Scientific Advisor , Consulting fee .

G. K. Swamy, Saol Therapeutics: Consultant and Scientific Advisor , Consulting fee .

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