The presence of interferon and type A immunoglobulins in the nasopharyngeal secretions of volunteers immunized with an inactivated influenza vaccine

The presence of interferon and type A immunoglobulins (IgA) was followed up in the nasopharyngeal washings collected from volunteers immunized intranasally with an inactivated influenza vaccine [strain A/Rom 1/73 (H3N2)]. Interferon was detected 24 hours after vaccine administration, its incidence being similar to that in the course of acute infection. Intranasal administration of inactivated influenza vaccine stimulated the production of secretory IgA in 3 of 10 samples collected 12 days after vaccination. At the same time, IgA were found in 4 samples collected before vaccination, and inhibited in certain cases the stimulation of interferon synthesis. The practical importance of the route of influenza vaccine administration is discussed.