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

The sponsors of the study had no role in data analysis, data interpretation, or writing of the report. The corresponding author had full access to all the data in the study and had final responsibility for deciding to submit the work for publication. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 previous studies showed that influenza activity is frequently out of phase with the hemispheric winter in many tropical regions and some temperate ones, with the consequence that optimal timing for routine influenza+vaccination recommendations does not necessarily correspond to the activity expected for that hemisphere. 5 Brazil, which includes temperate and tropical regions, exhibits an important regional heterogeneity in influenza peak. 6, 7 Seasonal influenza epidemics are usually associated with "cold+dry" and "humid+rainy" climates 8 ; however, in addition to climate and environmental conditions, host factors, such as age, preexisting immunity, genetic polymorphisms, and presence of comorbidities, are associated with seasonal variations of this infection, vaccine responsiveness, as well as the severity of influenza epidemics. 9 Vaccination is the main public health measure used to reduce the frequency of severe influenza cases. 2 In Brazil, influenza vaccination has been performed annually since 1999. Initially, immunization targeted individuals aged ≥65 years; however, in 2000, the age limit was lowered to 60 years. In 2016, the Brazilian Ministry of Health extended the recommendation to children <5 years, pregnant women, people with 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 procedures were performed according to approved protocols, and consent was obtained from all patients (or guardians).