A single-radial-immunodiffusion technique for the assay of influenza haemagglutinin antigen. Proposals for an assay method for the haemagglutinin content of influenza vaccines.

Single-radial-diffusion techniques are proposed as possible alternatives to tests based on agglutination of erythrocytes for the assay of the haemagglutinin content of influenza vaccines. Two test procedures (microtest and macrotest) and the use of reference reagents to assay vaccines using these tests are described. The two tests are of similar reproducibility and accuracy but the macrotest is technically simpler to perform and results of assays may be obtained more rapidly.