Najera-Morrondo, RafaelPerez-Breña, PilarFernández, M VLopez-Galindez, Luis CecilioLlacer Gil de Ramales, AliciaNájera, ESchild, G C2019-06-052019-06-051981Bull World Health Organ. 1981;59(1):79-83.0042-9686http://hdl.handle.net/20.500.12105/7733The immuno-double-diffusion (IDD) test was used to detect antibodies against the prevalent influenza A (H3N2) viruses in sera collected weekly in Madrid from 1972 to 1975. A total of over 14 000 sera were tested. The proportion of sera positive in the IDD test was found to reflect the level of recent influenza A infection of the population.engVoRAntibodies, ViralHumansImmunodiffusionInfluenza A virusInfluenza, HumanSpainAtribución-NoComercial-CompartirIgual 4.0 Internacional679018259179-83Bulletin of the World Health Organizationopen access