Estimating the burden of influenza-associated hospitalization and deaths in Oman (2012-2015)

Background: Influenza is a serious vaccine-preventable disease with high incidence, hospitalization, and mortality in high-risk groups. The epidemiology, seasonality, and risk factors for influenza are well defined in most of the temperate countries, but estimating influenza burden in the World Health Organization (WHO) Region for the Eastern Mediterranean is scarce. In Oman, despite the advancements in influenza surveillance, the clinical burden and seasonality of influenza remain not fully understood. Objectives: To estimate the incidence of influenza-associated hospitalizations and in-hospital death in Oman. Patients and methods: Influenza-associated hospitalizations and in-hospital deaths were estimated using hospital discharge records based on ICD-10 codes (J09-J18), results of virological analysis and population census for the period between 2012 and 2015. Results: During 2012 and 2015, we identified a total of 19 405 influenza-associated hospitalization and 847 deaths. Influenza positivity percentage ranged from 6.4% in 2013 to 20.6% in 2015. Influenza-associated hospitalization incidence rate was 7.3 (95% CI: 6.4-8.1) per 100 000 in 2013 and 27.5 (95% CI: 25.9-29.1) per 100 000 in 2015 with an overall rate of 20.6 (95% CI: 19.9-21.3) per 100 000. The highest incidence of influenza-associated death was among those aged ≥65 years and ranged between 39.5 (95% CI: 27.3-51.8) per 100 000 in 2014 and 11.3 (95% CI: 7.5-15.1) in 2015. Conclusions: Influenza causes a substantial number of hospitalizations and deaths in Oman. Hospitalization rates were highest among children, and adults ≥65 years showed the highest death rate. The potential value of using seasonal influenza vaccine in these groups should be considered.