Newborn infants are passively protected against certain viral diseases by transplacental transmission of immune antibodies. Ehrlich,1 in his study of antitoxin immunity to ricin, showed that passive transfer from immune mothers to their offspring occurs naturally. This transfer has been demonstrated by neutralization tests for poliomyelitis2 and for influenza, yellow fever, smallpox, and cowpox vaccine.3 Laboratory tests are not available for the transmission of antibodies for the virus of chickenpox.
Clinical observation suggests that there is transplacental transmission of immune antibodies against varicella. Most mothers have had this disease before they become pregnant. Its occurrence is rare in young infants. The records of Willard Parker Hospital in New York show that among 2200 admissions of patients of all ages for varicella during a three year period there was only 1 case of chickenpox in a newborn infant (0.05%) and only 46 cases in the age group from