Different features of influenza A H1N1pdm09 virus infection among adults in 2009/10 and 2010/11
Introduction: Influenza A H1N1pdm09 virus infection causes an epidemiologically and clinically severe disease mostly characterized by pneumonia, resulting in a high mortality rate. The purpose of this study was to investigate and compare epidemiological and clinical characteristics of influenza A H1N1pdm09 virus infection in patients hospitalized during the pandemic (2009/10) and post-pandemic seasons (2010/11).
Methodology: The data of patients with laboratory-confirmed influenza A H1N1pdm09 virus infection hospitalized and treated at the University Hospital for Infectious Diseases Dr. Fran Mihaljevic in Zagreb, Croatia in the first two seasons of appearance were analyzed.
Results: Compared to the pandemic season, in the post-pandemic season, patients were hospitalized longer, had higher values of inflammatory parameters, and were more often treated with antibiotics. The total number of risk factors in patients did not vary significantly between the two seasons. In the pandemic season, a significantly higher number of obese patients and patients with chronic lung disease was observed, whereas in the post-pandemic season, a statistically significant number of patients presented with symptoms of chronic cardiac and neuromuscular diseases. Primary viral pneumonia was frequently registered in younger adults during the pandemic season, whereas in the post-pandemic season, there were more cases of bacterial pneumonia.
Conclusions: During the pandemic season, the influenza A H1N1pdm09 virus infection caused a severe disease with rare bacterial complications, especially in adult patients. The common characteristics of the influenza A H1N1pdm09 virus were lost in the post-pandemic season, assuming the shape and characteristics of the seasonal influenza A virus.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).