A controlled trial of inactivated monovalent influenza A vaccines in general practice.

A trial of influenza A vaccines in general practice is described. Five hundred and seven subjects were vaccinated with either inactivated monovalent A/Hong Kong vaccine, A/England vaccine or influenza B vaccine as control. Local reactions were noted in 24% and general reactions in 12% of patients. Antibody titres in serum were measured by haemagglutination inhibition (HI) and complement fixation (CF) tests in 465 subjects. The influenza vaccines produced substantial increases in both homologous and heterologous antibodies as measured by the HI test and a comparatively poor response as measured by the CF test. Although clinical influenza was confirmed in only a few cases, there was serological evidence of significant subclinical infection in the control group.