Intradermal administration of bivalent and monovalent influenza vaccines

Intradermal (ID) administration of 0.1 ml of a bivalent influenza vaccine containing 40 CCA units each of influenza A/New Jersey (Hswine 1N1) and A/Victoria (H3N2) virus antigens and of a monovalent vaccine containing 100 CCA units of influenza B/Hong Kong virus to 70 adult volunteers produced no serious reactions and only 7% bothersome side effects. Excluding persons with high (1:64 or greater) initial antibody titers, then 90% and 85% of persons had fourfold or greater rises in HAI antibodies to A/New Jersey and B/Hong Kong antigens, whereas 53% had rises to A/Victoria. The authors feel the ID route deserves further consideration for giving killed influenza vaccines to adults. However, an influenza virus type that was prevalent for many years may fail to give sufficient rise in HAI to consider the patient protected.