Changes in Epidemiology, Clinical Features and Severity of Influenza a (H1n1) 2009 Pneumonia in the Post - Pandemic Influenza Season (Jan 2011 to Jan 2014)

Abstract

Although the influenza A (H1N1) 2009 virus is expected to circulate as a seasonal virus for some years after the pandemic period, its behaviour cannot be predicted. We analyzed a prospective cohort study of hospitalized (admitted) patients with influenza A (H1N1) 2009 pneumonia in MBS hospital in Kota to compare the epidemiology, clinical features and outcomes of influenza A (H1N1) 2009 pneumonia between the pandemic period and post-pandemic influenza season (Jan 2011 to Jan 2014). A total of 364 patients were included: 340 during the pandemic period and 34 during the post-pandemic influenza season .Patients during the postpandemic period were older and more likely to have chronic obstructive pulmonary disease, diabetes than the others. Septic shock, altered mental status and respiratory failure on arrival at hospital were significantly more common during the post-pandemic period. In addition, length of stay was longer, and need for mechanical ventilation and intensive-care unit admission were significantly higher during the post-pandemic period. In-hospital mortality (29.41%) in post pandemic period was higher than pandemic period (7.94%) was also greater during this period. In conclusion, significant epidemiological changes and an increased severity of influenza A (H1N1) 2009 pneumonia were found in the post-pandemic influenza season. Physicians should consider influenza A (H1N1) 2009 when selecting microbiological testing and treatment in patients with pneumonia in the upcoming influenza season.