Abstract
During the past year from December, 1942, to May, 1943, rather extensive studies were conducted for the purpose of determining the value of subcutaneous vaccination with inactivated influenza virus against the natural disease in man. The anticipated outbreak of influenza did not occur but the opportunity to test the resistance of certain of the vaccinated individuals to induced infection presented itself.
The vaccine represented the allantoic fluid of fertile hen's eggs infected 48 hours previously with either the PR8 strain of influenza virus, Type A, or the Lee strain, Type B. The virus was concentrated by the procedure of Francis and Salk, 1 inactivated with formalin 1:2000, and bottled and tested for sterility by the approved procedures for biological products. Phenyl mercuric nitrate, 1:100,000 was added for bacteriostatic purposes. The final vaccine was of such strength that 1.0 cc represented 5.0 cc of the original Type A fluid and 5.0 cc of Type B fluid.
The subjects were 102 physically active male residents of one ward of the Ypsilanti State Hospital, Ypsilanti, Michigan. On December 21, 1942, 45 received 1.0 cc of the vaccine subcutaneously. On April 21, 1943, 17 of these men again received 1.0 cc of the vaccine as did 21 men not previously vaccinated. There remained 28 men who had been vaccinated 4 months earlier and 36 individuals who had not been vaccinated at any time.
On May 4, 1943, 13 days after the last administration of vaccine, the entire group received an intranasal spray of the Baum‡ strain of Type A virus in allantoic fluid. The material was sprayed into the nostrils from a nebulizer with such fineness that approximately 0.5 cc was delivered in 4 minutes.
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