Immunization against Influenza A.

TN a previous paper (Hare, McClelland and Morgan, 1942) a method for the concentration and partial purification of influenza A virus in the allantoic fluid of developing hen's eggs was described. Suspensions of virus prepared in this way, inactivated with formaldehyde and frozen and dried, have been employed for the immunization of groups of persons in various parts of the Dominion during the winter of 1942-43. Various methods of dosage were employed and comparison made between the value of concentrated virus suspensions and vaccines made from allantoic fluid without alteration. This paper is an account of these experiments.