Global Influenza Hospital-based Surveillance Network (GIHSN): results of surveillance of influenza and other respiratory viruses in hospitalised patients in Brazil, 2015

Raboni, Sonia M; Moura, Fernanda EA; Caetano, Braulia C; Avanzi, Valéria M; Pereira, Luciane A; Nogueira, Meri B; Vidal, Luine R; Tavares, Isabel CF; Pradel, Florence K; Picot, Valentina S; Puig-Barbera, Joan; Siqueira, Marilda M

Patients of all ages who were admitted for any acute condition described as potentially associated with influenza were considered eligible for enrollment in the study. To be included, eligible patients were identified in the hospital admission registries and had to comply with all of the following criteria: 1) admission within 24 h to 72 h prior to recruitment; 2) a resident of the area of the study (defined for each site) and belonging to the base population source; and 3) a referral history for any acute condition associated with influenza and exhibiting onset within ≤7 days prior to hospital admission. This study used the European Center for Disease Control definition for ILI, which included at least one of four systemic symptoms (fever, headache, myalgia, or malaise) and at least one of three respiratory symptoms (cough, sore throat, or shortness of breath). Patients who did not give consent to participate, institutionalized individuals, and those with a history of hospitalization ≤30 days prior to recruitment were excluded from the study.