[The virological study of a certified focus of acute respiratory diseases in a half-closed community].

An acute respiratory disease outbreak appeared during February and March 1988 in a half-closed community. Virologic investigations were conducted and an influenza virus type B strain was isolated, antigenically like B/Victoria 2/87. Administration of the anti-influenza vaccine in the fifth day of the outbreak evolution led to considerable reduction of the new cases and to outbreak extinction after 48 hours.