Interest in the control of mumps is usually heightened during wars because of the prevalence of the disease among troops1 and the consequent danger of outbreaks in crowded civilian groups.
Control based on isolation of patients and quarantine of exposed persons is often ineffective, largely because the infection is highly communicable before the onset of symptoms and the recognition of the disease.2
Efforts to prevent infection by increasing the resistance of susceptible persons have been limited to passive immunization with convalescent blood or serum.3 The results of such measures have varied greatly. Although many investigators have reported protection of all or almost all of the persons inoculated,4 some have had a sufficiently large percentage of failures to introduce doubt as to the prophylactic value of the procedures employed.5 These differences are not easily explained.6 They reflect the existence of variables which make interpretation of