Edmondson, W. P., Jr., R. Rothenberg, P. W. White and J. M. Gwaltney, Jr. (Univ. of Virginia School of. Medicine, Charlottesville, Va. 22901). A comparison of subcutaneous, nasal, and combined influenza vaccination. II. Protection against natural challenge. Amer J Epidem 93: 480–486, 1971.—Monovalent killed influenza A2 Hong Kong vaccine in doses (400 CCA units) recommended for civilian use was given to insurance company employees and elderly psychiatric patients by injection, nasal spray, or a combination of both methods. Vaccinees and controls were then studied for evidence of immunity to influenza during the 1968–1969 epidemic Parenteral vaccination was well tolerated and effective in reducing influenza infection and illness rates in both groups. Vaccine had no effect on total respiratory illness in the insurance group, although total absenteeism was lowered because of the greater effect of influenza over that of colds in causing time lost from work. Vaccine given by spray into the respiratory tract was ineffective. The addition of spray to parenteral vaccination provided no additional advantage over parenteral vaccination alone.