Burden and Outcomes of Viral Respiratory Infections Among Adults in Bahrain: A Retrospective Cohort Study

Background Viral respiratory infections remain a major cause of morbidity and mortality among adults, particularly those with chronic comorbidities. In Bahrain, most available evidence is derived from surveillance-based datasets that are limited by underreporting and incomplete clinical information. This study provides a comprehensive assessment of the burden, testing patterns, and outcomes of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), influenza, and respiratory syncytial virus (RSV) among hospitalized adults using detailed clinical data from a major tertiary hospital. Methods A retrospective cohort study was conducted among patients aged ≥14 years admitted to Salmaniya Medical Center, Bahrain, with acute respiratory illness during the 2023-2024 winter season. Demographics, comorbidities, admission diagnoses, viral testing results, antiviral use, intensive care unit (ICU) admission, mechanical ventilation, and mortality were extracted from electronic medical records. Descriptive statistics, chi-square/Fisher's exact tests, multivariate logistic regression, and Kaplan-Meier survival analysis with Cox proportional regression model were performed. Results Among 943 hospitalized adults, 482 (51.1%) were aged >60 years, and 681 (72.2%) were non-Bahrainis. Of all patients, only 625 (66.3%) underwent viral testing, reflecting non-standardized testing practices. SARS-CoV-2 positivity was 5.1% (32/625), influenza positivity 6% (10/162), and RSV positivity 5.2% (3/57). Chi-square test revealed that SARS-CoV-2 infection was significantly associated with female gender (p = 0.008), age >60 years (p = 0.045), diabetes (p = 0.009), and higher mortality (21.9% vs. 10.1%; p = 0.036). The multivariate regression analysis showed that being female (AOR 2.78, CI: 1.25-6.19, p = 0.012) and having diabetes (AOR 2.54, CI: 1.13-5.70, p = 0.024) were independent predictors of SARS-CoV-2 infection. Kaplan-Meier curves demonstrated that SARS-CoV-2-positive patients had significantly shorter time to discharge than SARS-CoV-2-negative patients (p = 0.016). Influenza infection was associated with chronic lung disease (p = 0.045) and bronchial asthma (p = 0.023), with no deaths or ICU admissions among influenza‑positive cases. A small sample size (n = 3) limited RSV findings. Conclusion SARS-CoV-2 infection was relatively uncommon but was associated with markedly worse clinical outcomes, including higher in-hospital mortality and shorter survival. Influenza and RSV positivity rates were higher but substantially under-tested, limiting accurate burden estimation. These findings highlight the need for standardized three-virus testing panels, earlier antiviral initiation, and targeted vaccination strategies for high-risk adults, particularly those with diabetes and chronic lung disease.