The primary objective of this observational study is to determine the incidence of medically attended (inpatient or outpatient) acute respiratory illnesses or events leading to worsening cardiorespiratory status (ie, acute exacerbations of chronic obstructive pulmonary disease [AECOPD] or worsening CHF) associated with RSV infections in high-risk adults (ie, those with severe COPD and/or advanced CHF) across multiple consecutive RSV seasons.