In case of negative, indeterminate or unknown sero-logic status, the application of VZIG within 72 (-96) hours has been recommended [47,48] (Figure 3) intramuscu-larly at a concentration of 125 U/10 kg of body weight, up to a maximum of 625 U [29] or 0.5 ml/kg of body weight [30]. A dosage of 1 ml/kg of body weight can be adminis-tered intravenously as alternative [30]. Even though the passive immunization does not prevent varicella, it may reduce most likely the risk of severe varicella as well as fetal infection. However, there is no evidence that this prevents fetal viremia or CVS. Thus, the primary reason for VZIG is to prevent severe maternal chickenpox and its complications, such as pneumonia. If there is a definitive past history of chickenpox, it is reasonable to assume that the woman is immune to varicella. Vaccinated pregnant women who were tested VZV IgG-negative should be managed as a seronegative pregnant woman without varicella vaccination. However, in most cases, seronega-tive vaccinees have most likely acquired VZV-specific cell-mediated immunity.