Inactivated vaccine against trivalent influenza: a comparative study of antigenicity by haemagglutination inhibition and simple radial haemolysis

Abstract

The inactivated vaccine anti-influenza virus, prepared at the Butantan Institute, containing 200 U.H. from each one these virus strains, Influenza A/SP/1/80 (H3N2), A/SP/1/78 (H1N1), B/England/847/73, was administered to 110 human volunteers in one and two doses to 62 and 48 persons respectively, with an interval of 21 days between these doses. The response to specific antibodies to influenza was analysed comparatively by the methods of Haemagglutination-Inhibition (HI) and Single-Radial-Haemolysis (SRH). These methods demonstrated a correlation between themselves, with a percentual correspondence in the negative HI titres, < 1:20 and diameter of haemolysis < 3.0mm. Correlation between the haemolysis zone of 3.5-5.0 mm diameter with HI titres of 1:40-1:80 was observed and titres of 1:160-1:320 by HI test were equal to haemolysis zones of 5.5 mm in diameter by SRH test. Very high HI titres >; 1:640, corresponded to hemolysis zones >; 7.5 mm in diameter. Soroconversion rate occurred those vaccinated, which corresponded to an increase of 4 times or more in the antibody titres obtained from the HI test and an increase of 3.0 mm or more in the haemolysis zone diameter.