VARIZIG Rx

Pregnant Women Exposed to Varicella Zoster Virus

A randomized, open-label, multicenter, active controlled clinical trial was conducted in 60 pregnant women without immunity to VZV (as confirmed by a latex agglutination test).

• Patients were stratified on the basis of time from first exposure to varicella as follows:
  
  • 1 to 4 days post-exposure and,
  • 5 to 14 days post-exposure.
• The women were randomly assigned into 1 of 3 study arms as follows:
  
  • a single IV dose of 125 IU/10 kg to a max dose of 625 IU of Varizig,
  • a single IM dose of 125 IU/10 kg to a max dose of 625 IU of Varizig or,
  • a single IM dose of 125 IU/10 kg to a max dose of 625 IU of VZIG (licensed comparator product).
• Patients were followed for 42 days.
• Incidence of clinical varicella was similar across all treatment groups with an overall incidence of 33%; however, in the subset of 28 patients with more than 24 hours exposure to varicella, the incidence of clinical varicella in the combined treatment groups was 64%.

High Risk Patients Exposed to Varicella Zoster Virus

An open-label, Expanded Access Protocol (EAP) conducted in the US was designed to provide Varizig to high risk individuals who were exposed to varicella zoster virus (VZV). The study was not designed to evaluate efficacy, however, the objective was to further assess and confirm the safety/efficacy of Varizig IM injection in the prevention or reduction of severity of complications from varicella infections in the indicated high risk populations. Initially, enrollment was limited to allow treatment with Varizig only within 96 hours of exposure, but later amended to a treatment window of 10 days post-exposure.

• The incidence of clinical varicella (chickenpox lesions), was compared to predefined historical reference rates.
• The incidence of severe varicella complications, including pneumonia, encephalitis, severe varicella with pox counts >100 pox, mortality and all complications was also evaluated.
• The overall incidence of clinical varicella was evaluated in an interim analysis, where 10% (31/311) of high risk individuals exposed to VZV and treated with Varizig for all combined populations, for whom complete or partial efficacy data was available.
• Clinical varicella was observed in 8.4% (13/154) of immunocompromised pediatric and adult patients, in 6.8 % (5/74) of pregnant women, in 14.8% (12/81) of infants and one healthy adult.
• Clinical varicella was more common after prolonged VZV exposure.
• The final report confirmed the efficacy results in the interim analysis.
• Updated final results of clinical varicella was observed in 4.5% (12/269) of immunocompromised pediatric and adult patients, in 7.3% (10/137) of pregnant women, in 11.4% (12/105) of infants (including newborns, preterm infants, infants aged <1yr). 

Moreover, a comparison of the incidence of varicella based on the treatment window revealed that treatment between 5 and 10 days post-exposure was no different from treatment within 96 hours.