[Epidemiological profile of pandemic influenza A cases in the south of Santa Catarina state, Brazil, in 2009].

OBJECTIVE: To describe the epidemiological features of influenza A (H1N1) cases in 14 municipalities of Santa Catarina, Brazil, during the 2009 pandemic.

METHOD: This cross-sectional study focused on suspected cases of H1N1 reported to the 20th Santa Catarina State Health Administration during the 2009 pandemic between July to September. Data were collected by epidemiological surveillance officers from the Brazilian communicable diseases information system SINAN. H1N1 cases were confirmed by laboratory testing (positive RT-PCR) or signs and symptoms characteristic of severe acute respiratory syndrome.

RESULTS: During the pandemic period, 1 149 suspected cases of influenza A were notified, of which 560 (48.6%) were confirmed. That translated into an incidence of 241.9/100 000 population. Mean age for confirmed cases was 29.5 ± 17.1 years, vs. 32.2 ± 20 years for those ruled out (P = 0.03). Of the total confirmed cases, 37.1% were hospitalized, with a hospital incidence rate of 89.9/100 000 people and lethality rate of 5.6/100 000 population. Age < 30 years, symptoms of fever, cough and dyspnea, and death were independently associated with influenza A infection (P < 0.05). There were no associations between confirmed cases and any comorbidities.

CONCLUSION: The studied sample differed from the national profile of influenza A cases in Brazil by the absence of associated comorbidities. However, it was similar to the national profile in terms of the young age of cases and the significant association with fever, cough, and dyspnea. An extension of the annual immunization campaign (currently focused on risk groups) to the overall population should be considered.