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

To better understand the seasonality of influenza infections in the study sites, we evaluated the monthly distribution of samples and viral positivity. Then, we plotted this information against the temperature and precipitation (historical means) recorded for each month. Results show variations between Northeast (Fortaleza) and South (Curitiba) Brazil in relation to the peak time of influenza infections, which essentially followed the rain season of each region. Finally, results indicate that immunization against influenza in the Northeast was carried out after the period of virus circulation ( Figure 3 ). Data from Rio de Janeiro were not evaluated owing to the small number of patients included in the study.