That convalescent blood when injected into infants exposed to pertussis confers a certain degree of protection appears to be established.1 Its value when injected after the onset of symptoms, however, has not been fully determined.
It would seem that the injection of immune serum during the catarrhal stage of pertussis would be indicated, since demonstrable antibodies do not normally appear until the height of infection occurs. Since the level of antibodies in the blood of recovered patients is relatively low, attempts have been made to increase the titer by inoculating immune adults with vaccine. Jundell2 gave injections of freshly prepared vaccine to donors a few days prior to the withdrawal of blood. Kendrick3 reported that the blood of hyperimmune donors was definitely protective when given to exposed infants. McGuinness, Stokes and Mudd4 suggested that hyperimmune human serum possesses definite prophylactic value. They also reported that 5