Influenza in the USSR in 1977: recurrence of influenzavirus A subtype H1N1.

Abstract Early in November 1977, several outbreaks of influenza were reported in the far eastern region of the USSR. The epidemic spread rapidly throughout the country affecting mainly people under the age of 20 years. Most of the strains of virus isolated were found to be influenza A subtype H1N1. The serological characterization of the strains is described in this paper.