Decision model structure. In each age group, persons could be vaccinated or unvaccinated, depending on vaccination policy and coverage (node 2). Both vaccinated and unvaccinated persons are at risk of influenza (node 3) and may or may not receive treatment for this condition (node 4). Pneumococcal disease sub tree. In the model, persons are first subject to the risk of meningitis (node 5), which can lead to death (node 6) or to deafness, disability, or no sequelae (node 7). Those not experiencing meningitis are subject to the risk of bacteremia (node 8), including bacteremic pneumonia, which may lead to death (node 9). Similarly, persons who do not contract meningitis or bacteremia are then at risk for non-bacteremic pneumonia (node 10) and AOM (node 11), and they can die of pneumonia (nodes 12). Persons may also die of causes unrelated to pneumococcal disease; these deaths are incorporated into the event-specific mortality probabilities (at nodes 6, 9, 12, and 14), and are captured separately for those who avoid acute pneumococcal events (node 13).