Usefulness of Clinical Definitions of Influenza for Public Health Surveillance Purposes

Domínguez, Àngela; Soldevila, Núria; Torner, Núria; Martínez, Ana; Godoy, Pere; Rius, Cristina; Jané, Mireia

For the WHO and ECDC ILI case definitions, the overall sensitivities were 82% and 58%, and the specificities were 37% and 52%, respectively. A 2009-2014 French study [9] found higher sensitivities (89.8% for the WHO definition and 96.1% for the ECDC definition) but lower specificities (21.4% for the WHO definition and 6.6% for the ECDC definition). The differences may be because we only knew that patients had a temperature of >37.8 • C, instead of the required temperature of ≥38 • C stated in the WHO definition, and because in the French sentinel network, the ARI definition was an inclusion criterion, and nearly all patients included in the dataset had fever [25] . However, as in the French study, the WHO case definition of ILI was a better discriminator than the ECDC definition in our study.