Prevention from naturally acquired viral respiratory infection by interferon nasal spray

Human leukocyte interferon (IFN-alpha), 50,000 IU per day, was sprayed into the nasal cavity of 73 volunteers twice a day from January 9 till March 4, 1984. The rise in complement fixation antibody titers against influenza A virus was not significantly different between the interferon group and the placebo group. However, the number of subjects without elevated antibody titers and without symptoms in the interferon group was significantly higher than that in the placebo group (p less than 0.05). Prophylactic nasal spray of IFN-alpha seems to protect against upper respiratory viral infection.