Passive Immunity to Vaccinia in Newborns

A hemagglutination-inhibition test for the determination of vaccinia antibodies in serum was first described by Nagler.5 It has been used extensively by us in a standardized form.2 Collier8 has utilized a modification of the method in his study of adults. The present report deals with the determination of the titre of vaccinia antibodies in the sera of 182 mothers at term and in the cord blood of their newborn offsprings. Of the mothers, 102 had been vaccinated within the past five years, while 80 had been vaccinated more than five years ago.