Clinical profile of influenza virus-related hospitalizations in children aged 1-59 months: A five-year retrospective study from south India.

Background: Influenza is a seasonal acute respiratory tract infection with different strains in circulation at different time periods with varying spectrum of clinical presentation.

Objectives: To study the clinical presentation, morbidity, and mortality patterns associated with different strains of influenza virus, to identify the predominant strains related to hospitalization, and to identify the seasonal trend in hospitalization and risk factors for mortality in children aged 1-59 months hospitalized with influenza.

Materials And Methods: The records of children hospitalized with influenza were analyzed retrospectively (June 2013 to June 2018). Anonymized data from the Medical Records Department of our Institute, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), were used for the study and waiver of consent was obtained from the Institute Ethics Committee for Human Studies (JIPMER), which also approved the study. The data from the medical records were extracted as per the proforma and entered into Microsoft excel and summary statistics was obtained. Categorical data were expressed as proportion and analyzed using chi square test. Association was tested using odds ratio.

Results: Of the 693 children tested for influenza during the study period, 91 were found to be positive for influenza infection and out of which 68 (74.7%) were hospitalized. Infection was seen during both the summer and winter months. The predominant strain being A (H1N1) pdm09 (63.2%). The other strains found were A (H3N2) and Influenza B. The predominant diagnosis was pneumonia. The need for mechanical ventilation was more common with influenza B infection (p = 0.035). No significant risk factors for mortality could be found in our study.

Conclusion: An absence of seasonal predilection for the disease was noted with influenza A (H1N1) pdm09 being the predominant strain with influenza B seen as an emerging strain and an important contributor towards morbidity.