Background: Influenza A (H1N1) is an acute respiratory infection caused by influenza virus H1N1 subtype A. It is highly contagious virus. It causes significant morbidity and mortality and spread in community. Objectives: To identify epidemiological characteristic including seasonal pattern of hospital based patient suspected with H1N1 infection. Methods: Hospital based retrospective study was designed from January 2017 to December 2019. The data was collected from District Hospital Amravati, Maharashtra. Results: In the present study, a total of 547 samples were tested and 127(23.21%) were recorded positive for H1N1. Most numbers of these cases were from young adults (34.55%) in age group between 15-30 years and less were observed in old age group (10.23%) in age group of >60 years. Female (58.26%) were
infected more than male (41.73%). Total two peaks of infection were noticed. One was summer season (April) & second was in winter season (October) in year 2017 while one peak of infection was noticed in winter season in year 2018 and 2019. Conclusion: Epidemiological parameters and seasonal pattern of Influenza A (H1N1) gives ideas to create the awareness and to improve the control strategies to minimize the morbidity & mortality and spread of disease.

Keywords: Influenza A (H1N1), Seasonal trend, Epidemiological characteristics.