[Antineuraminidase activity of inactivated influenza vaccines in elderly people]

The antineuraminidase activity of 5 inactivated split and subunit influenza vaccines (IIV) was studied in individuals aged above 65 years. Postvaccinal antibody titers were determined in the lectin test. All the vaccines were shown to have a high antigenicity, by providing high titers of neuraminidase antibodies in most vaccinated persons: The mean geometric titers (MGT) to influenza viruses A(H1N1) and A(H3N2), and B were 7.4-8.0, 8.5-9.2, and 6.8-8.5 log2, respectively. Neuraminidases showed a higher activity in Vaxigrip-vaccinated persons in terms of both the rate of MGT increases and seroconversion that was 78-84%. The parameters of the anti-neuraminidase (anti-NA) and anti-hemagglutinating (anti-HA) activities of IIV are summarized in the paper. There was a high coincidence of the results of both tests. At the same time it was shown that the postvaccinal humoral immune response might be directed only to one of the surface influenza virus proteins. The highest rate of seroconversions as to the surface antigens of all three influenza viruses was observed in Vaxigrip-vaccinated persons. The paper presents the results of comparison of the levels of MGT of antibodies to both viral surface proteins for all vaccinated with IIV, for those vaccinated who were infected during an epidemic season and a place group. The findings confirmed the value of higher titers of postvaccinal antibodies against influenza infection and illness.