[Etiologic and immunologic characteristics of the influenza A1 epidemic in the Khabarovsk region in November--December 1977].

The etiology of an influenza outbreak which had occurred in Khabarovsk since 14 November, 1977 was elucidated. The largest number of cases was recorded among children and adolescents (under 22 years of age). Virological studies during the epidemic yielded 90 strains of influenza virus which were found to be antigenically quite close to A1 virus (HINI) which had circulated in this country in 1947-1956.