Burden of Disease of Respiratory Syncytial Virus in Older Adults and Adults Considered at High Risk of Severe Infection

Abstract Background Vaccine products for adults have increased interest in understanding Canada’s respiratory syncytial virus (RSV) burden in older adults and adults considered at high risk of severe infection. Objective To characterize the burden of RSV disease in Canada by joint analysis of the published literature and hospitalization data from a healthcare administrative database. Methods Electronic databases of published literature were searched to identify studies and systematic reviews reporting data on outpatient visits, hospitalizations, intensive care unit (ICU) admissions and deaths associated with RSV infection in adults. For the hospitalization data analysis, hospital discharge records were extracted from the Canadian Institute of Health Information (CIHI) Discharge Abstract Database (DAD) for all patients admitted to an acute care facility for RSV infection defined by ICD-10 codes from 2010-2020 and 2021-2023. Results Overall, 26 studies, including 7 systematic reviews, were identified and summarized in the rapid review. Evidence suggests that medically attended RSV respiratory tract infections (RTI) are frequent causing 4.7 to 7.8% of symptomatic RTI in adults 60 years of age and older. Incidence of RSV RTI increases with age and presence of underlying medical conditions, such as cardiorespiratory disease, diabetes, and immunocompromising conditions. This trend was consistently observed across all RSV clinical outcomes of interest (i.e., hospitalization, ICU admission and death). Patients who reside in long-term care or other chronic care facilities have higher likelihood of severe clinical outcomes (i.e., ICU admission, receiving mechanical ventilation and/or death) compared to patients with other living situations upon hospital admission. Approximately 10% of older adults hospitalized with RSV infection require ICU admission. Although data are limited, evidence suggests that case fatality ratio (CFR) among those admitted to hospital varies between 5 and 10%. Some evidence suggests that RSV burden may be close to influenza burden in older adults. In general, the results from the Canadian hospitalization data support the rapid review findings Rates of hospitalization, ICU admission and death associated with RSV all increased with age, with 16% of hospitalizations resulting in ICU admission and with an in-hospital CFR of 9%. Conclusion In adults, risk of severe RSV outcomes in general increases with increasing age and presence of comorbidities.