Characteristics of medically attended influenza infection across age groups before the COVID-19 pandemic in Lebanon

Abstract

Background: Influenza represents a significant global health burden for individuals and society. This study assessed the burden of medically attended influenza at a tertiary medical center in Lebanon to describe the demographics, risk factors, and outcomes prior to the COVID-19 pandemic.

Methods: This was a retrospective review of patients who tested positive for the influenza virus during three seasons between July 1, 2016 to June 30, 2019, at the American University of Beirut Medical Center.

Results: A total of 2049 patients who tested positive for influenza were analyzed. Influenza A accounted for 79.6 % of cases, and influenza B for 19.7 %, with influenza activity starting in October/November and peaking in December/January. Older age above 65 years (AOR=3.584), obesity (AOR=2.183), and chronic conditions such as chronic lung diseases (AOR=1.832), and bacterial co-infection (AOR= 2.834) were found to be independent risk factors for developing complications. Viral co-infection increased the likelihood of death tenfold. Vaccinated patients had a shorter mean hospital stay duration and a lower intensive care unit admission rate.

Conclusion: The burden of medically attended influenza at our tertiary medical center in Lebanon prior to the COVID-19 pandemic was high. Vaccination decreased the likelihood of complications leading to intensive care unit admission in patients at risk.

Keywords: Burden; COVID-19 pandemic; Influenza; Lebanon; Seasonality; Vaccination.