Epidemiologic Characteristics and Clinical Outcomes of Respiratory Syncytial Virus in Hospitalized Care in Lebanon: A Prospective Observational Study

Sarah Khafaja¹Sara Merkhi¹Stephanie Damaj¹Saja Issaoui¹Celina Boutros¹Habib Al-Kalamouni¹Nadia Soudani¹Yolla Youssef¹Zeinab El-Zein¹Samer Bou Karroum¹Ahmad Chmaisse¹Magda Haj¹Zeina Houry¹Sarah Chamseddine¹Nour Youssef¹Rouba Shaker²Amal Naous³Soha Ghanem³Chantale Lahoud⁴Imad Chokr⁴Rita Feghali⁴David Breish⁵Amani Haddara⁶Maria Karam⁶Hassan Zaraket^1*Ghassan Dbaibo^1*

• ¹American University of Beirut, Beirut, Lebanon
• ²New Mazloum Hospital, Tripoli, Lebanon
• ³Makassed General Hospital, Beirut, Lebanon
• ⁴Rafik Hariri University Hospital, Beirut, Lebanon
• ⁵Bekaa Hospital, Bekaa, Lebanon
• ⁶Keserwan Medical Center, Ghazir, Lebanon

Introduction: The aim of this study was to describe the epidemiology and clinical outcomes of respiratory syncytial virus (RSV) infection in hospitalized children and adults from a sentinel surveillance network in Lebanon, and to compare the RSV rates and seasonality before and during COVID-19 pandemic. Methods: This study was based on the data from the Lebanese component of the Global Influenza Hospital Surveillance Network (GIHSN) during three consecutive seasons between 2019-2021 at six hospitals, following a standardized protocol based on age-specific criteria. Specimens were tested for RSV. Descriptive statistics were used to summarize demographics, RSV rate, and outcomes. Univariate analyses were performed using Pearson's Chi-square or Fisher's exact test, and associations were expressed as unadjusted odds ratios (95% CI). A p-value ≤0.05 was considered significant. Results: From January 2019 to September 2021, 2,626 of 7,081 eligible inpatients were enrolled in the study, with 188 tested positives for RSV (7.3%). The majority (74.5%) of RSV-positive subjects were children under five years of age, and 9.6% of patients were ≥ 65 years of age. The positivity rate varied across seasons (2.1%-11.1%); the 2020-2021 season —was disrupted by COVID-19 pandemic — recording the lowest rate of 1.1% during the typical winter months followed by an off-season RSV resurgence. Fever, cough, nasal congestion, wheezing, neurological symptoms, diarrhea and decreased oral intake were significantly associated with RSV infection (p < 0.05). Cough and wheezing were predominant in RSV-positive children <5 and adults aged ≥ 65 years. Among RSV-positive subjects, 8% required ICU admission, 5.3% received mechanical ventilation, and 2.7% died. Severe outcomes were more common in those ≥65 years, and the presence of ≥2 comorbidities and underlying cardiovascular disease significantly increased the risks of mechanical ventilation (OR= 7.44 [1.13-48.99], p-value 0.037 and OR= 8.32 [2.20-31.37], p-value 0.004, respectively) and in-hospital death (OR= 22.67 [1.91-268.50], p-value 0.013 and OR= 11.50 [1.82-72.85], p-value 0.016, respectively). Conclusions: Given the recent rollout of RSV vaccines and monoclonal antibodies, continued surveillance is needed to monitor changes in epidemiology, seasonality, and disease burden, especially in low-and middle-income countries.