Disease burden is an indicator of health outcome. Disease burden can be expressed in many ways, such as the number of cases (e.g. incidence or prevalence), deaths or disability-adjusted life years lost (DALYs) associated with a given condition

Information on the reported incidence of vaccine-preventable diseases is provided by countries to WHO. Such information usually underestimates the actual number of cases, but nevertheless can provide useful information on trends, epidemiology of disease, and susceptibility in the population in order to guide public policy, strategy, and disease control activities

WHO provides estimates of the burden of disease based on methods which utilize information from a variety of sources - demographic data, vital registration data, immunization coverage levels, and clinical studies

Distribution of the estimated deaths among children under 5 years of age, from diseases that are preventable by vaccination in 2008:

• Hib: 199 000
• Pertussis: 195 000
• Measles: 118 000
• Neonatal tetanus: 59 000
• Tetanus (non-neonatal): 2 000
• Pneumococcal disease: 476 000
• Rotavirus: 453 000

WHO provides protocols and guidelines on assessing disease burden using a variety of methods such as disease surveillance, rapid assessments, or population-based studies