Protective Effect of Vaccination Against Induced Influenza a 1

In December 1942, rather extensive studies, which will be reported separately, were begun for the purpose of determining the value of subcu- taneous vaccination with a vaccine of inactivated influenza viruses, Types A and B, against the epidemic form of influenza. The anticipated out- break of this disease did not occur but the oppor- tunity to test the resistance of certain of the vac- cinated individuals to induced infection presented itself. This was done by inducing infection with strains of virus maintained under laboratory con- ditions. Other investigators (1) had previously reported that, by the use of such a procedure, vac- cine containing inactivated Type A influenza virus, given subcutaneously, was demonstrated to have protected children against experimental infection.