Spectrum and Burden of Influenza Infection: An Approach to Identify Predictors of Morbidity and Mortality Rate from the Patients of the Northwest of Iran.

Background: The objective of this research is to analyze influenza-induced complications, symptoms, and the interaction of morbidity and mortality rates in hospitalized influenza cases based on age-sex dispersion, influenza virus subtype, prescribed medications, and underlying conditions. Materials and Methods: We performed this retrospective study using a dataset of 10,517 hospitalized individuals, including 3,101 laboratory-confirmed influenza cases from patients of all ages who had attended hospitals in the Northwest of Iran due to respiratory complications. Results: The most prevalent strain which circulated annually was influenza A/H3N2. In contrast to previous studies, our findings suggested that influenza A/H1N1 has the highest mortality rate and the most severe complications.Regardless of virus type/subtype, the most susceptible age group for influenza was 0-9 years old in both males and females. Meanwhile the high-risk age group among males was 50-59 years old and among females were over 80 age group (mortality rate ≈ 20%). Chronic obstructive pulmonary disease (COPD) (32%) and cardiovascular disease (CVD) (30%) were the most prevalent active underlying diseases among the patients who died, with the latter being more prevalent in males over the age of 70. Patients with a history of chemotherapy had the highest mortality rate. Patients who were prescribed a combination of antibiotics and antivirals had better outcomes with lowest mortality rate. Conclusion: Our findings demonstrated that annual influenza seasons are often marked by changes in influenza types and subtypes, with variations in the severity. Development of a standardized set of arrays that best correspond with infections, can be useful in guiding diagnostic and therapeutic decisions.