Table 5 Additional aspects that need consideration in the elderly

• Burden of pneumococcal disease varies in different regions

  - Different rates of risk factors such as smoking, HIV, other comorbidities in the population or community

• Herd protection may be different geographically as may the residual burden of disease

  - Different susceptibilities of the hosts, which childhood vaccines are used, and their coverage rate, force of transmission, proportion of disease caused by vaccine serotype

• Does herd protection have a limit?

• Decline of PCV13 serotypes in adults is attenuated by older age and comorbidity

• Underestimation of residual pneumococcal disease

  - Especially of non-invasive infection, and/or when using conventional microbiological methods only

• Serotype replacement disease

  - Varies in different countries