Surveillance of influenza A and B viruses in Italy between 1984 and 1987.

Antigenically heterogeneous strains and new variants of influenza A viruses, both A (H3N2) and (H1N1) subtypes, as well as influenza B strains were detected in Italy in a period, between 1984-1987, characterized by a moderate degree of influenza activity. Each year the evaluation, by SRH technique, of antibodies, in the population, to currently circulating viruses, has confirmed the extent of infection and often the prevalent virus.