Associated seroconversions to respiratory viruses in volunteers with experimental influenza infection.

Serological examinations of 573 volunteers with mild experimental influenza infection and 86 volunteers of a control group hospitalized in a special clinic revealed a significant rise in the titre of antibodies (seroconversion) not only to influenza A or B viruses used for the experimental infection but in 23.3 to 29.8% of cases also to other respiratory viruses. Based on a number of arguments, associated seroconversions are interpreted as due to mixed or sequential infections of different aetiology.