Respiratory Syncytial Virus burden among Ugandan Adults Aged ≥65 Years: A 15-Year Sentinel Surveillance Study of Prevalence, Coinfections, and Comorbidities (2010–2025)

Background: Respiratory syncytial virus (RSV) is an important cause of acute respiratory illness in older adults, yet data from sub-Saharan Africa remain scarce. Understanding prevalence, coinfections, and risk factors in this age group is critical for guiding surveillance and prevention. Methods: We conducted a retrospective cross-sectional study using Uganda’s national influenza-like illness (ILI) and severe acute respiratory infection (SARI) sentinel surveillance data from December 2010 to January 2025. Adults aged ≥65 years with Real time-PCR (RT-PCR) results for RSV, influenza A/B, and SARS-CoV-2 were included. Descriptive analyses summarized period prevalence, clinical characteristics, and temporal trends. Poisson regression with robust variance estimated adjusted prevalence ratios (aPRs) for factors associated with RSV infection and hospitalization. Results: Among 545 illness episodes (mean age 73.2 years; 54.1% female), the period prevalence of RSV across 2010–2025 was 4.8% (95% CI: 3.3–6.9), comparable to influenza A (4.2%) and lower than SARS-CoV-2 (6.4%). Most RSV cases were mono-infections (92.3%), with rare RSV–influenza coinfections (0.4%) and no RSV–SARS-CoV-2 coinfections. Asthma (aPR 6.08, 95% CI: 1.18–31.26, p=0.031) and pneumonia (aPR 2.83, 95% CI: 1.06–7.56, p=0.038) were independent predictors of RSV infection. Hospitalization was strongly associated with asthma (aPR 21.69, 95% CI: 7.50–62.71, p<0.001), pneumonia (aPR 3.80, 95% CI: 1.51–9.56, p=0.005), and heart disease (aPR 3.50, 95% CI: 1.03–11.91, p=0.045). RSV activity showed seasonal peaks in March and June, with a marked decline during 2020–2021 (COVID-19 restrictions) and resurgence thereafter. Conclusions: RSV is a consistent contributor to respiratory illness among older Ugandan adults, with period prevalence estimates similar to influenza A and clinically important associations with asthma and pneumonia. Seasonal peaks during the dry season and post-pandemic resurgence emphasize the need for RSV integration into surveillance and the timely introduction of preventive interventions, including vaccination, in low- and middle-income settings.