Chickenpox is usually a mild disease, and therefore no attempt is made in private practice to prevent its development in exposed persons. On the other hand, the presence of chickenpox in children's institutions and hospitals warrants the use of any procedure which may prevent the spread of the disease, as successive outbreaks may bring about a quarantine for months.
In 1923 Blackfan, Peterson and Conroy1 reported favorable results with the use of convalescent serum in the prevention of chickenpox. Forty-two susceptible children exposed five days previously were given 5 cc. of convalescent serum. Only seven of these children subsequently had chickenpox, and in every instance the disease was mild.
In 1924 Weech2 also reported favorable results with the employment of convalescent serum as a preventive agent. Of nine infants receiving from 3 to 4.5 cc. of convalescent serum from one to six days after exposure to chickenpox, eight