UNICEF and Immunization
Immunization against preventable childhood illnesses is an essential part of improving the health and well-being of children. Immunization campaigns are among the most successful and cost-effective public health interventions. Some experts suggest they have saved in the vicinity of 20 million lives in the last two decades. Figures on immunization coverage are available at Facts on Children and at Childinfo.
UNICEF annually purchases immunization supplies for children in some 100 countries, making it the leading global agency procuring vaccines for children. In 2010, UNICEF spent approximately $1.955 billion on supplies for children, of which about $757 million was used to purchase vaccines.
Immunization coverage of infants for the six major vaccine-preventable diseases – diphtheria, measles, pertussis, polio, tetanus and tuberculosis - rose from less than five per cent in 1974 to more than 75 per cent in 2006. Over the last ten years, data consistently shows that over 70 per cent of children under five years of age have been immunized against these illnesses.
However despite the success of immunization campaigns, millions of children remain unprotected and at risk from these life-threatening and debilitating diseases.
The vaccine regime called DPT comprises a series of immunizations to prevent diphtheria, pertussis and tetanus. To be fully immunized, children must receive three doses of the vaccine before their first birthday. Data about the status of DPT3 coverage is available at Childinfo.
Measuring the extent and effectiveness of vaccine coverage
Complete coverage with DPT (DPT3) is a particularly valuable indicator of countries' performance of routine immunization and is often considered among the best indicators of children’s access to basic services, including health services.
Immunization coverage estimates are used for a variety of purposes: to monitor the performance of immunization services at local, national and international levels; to guide polio eradication, measles control and maternal and neonatal tetanus elimination; to identify areas of weak system performance that may require extra resources and focused attention; and as one indicator when deciding whether to introduce a new vaccine.
Tracking, evaluating and sharing information provides a vital tool for understanding immunization coverage. Statistics on levels and trends are used to monitor the performance of services at local, national and international levels. (A statistical compendium of data on immunization is available at http://www.childinfo.org/files/Immunization_Summary_2008.pdf.)
Since June 2000, the World Health Organization (WHO) and UNICEF have annually reviewed national immunization coverage.
There are two sources of empirical data used to estimate immunization coverage: reports of vaccinations performed by service providers (administrative data) and household surveys that ask parents questions about their children's vaccination history (coverage surveys). The Expanded Programme on Immunization (EPI) 30 cluster survey, the UNICEF-supported Multiple Indicator Cluster Survey (MICS) and the Demographic Health Surveys (DHS) are the principal types of surveys used as sources of information on immunization coverage.
Both administrative and survey data provide valuable information on immunization coverage but neither, in itself, provide a reliable estimate of the extent of the protection that children are actually receiving. UNICEF believes that a more complete picture of immunization coverage, quality, and equity can be developed by using multiple sources of data and information.
In constructing their estimates of a nations’ immunization coverage, WHO and UNICEF systematically review survey and administrative data reported by governments, search the literature for additional data that may be available, and incorporate other country-specific information.
Because UNICEF has a field presence in some 150 countries, it has access to another essential tool for building more accurate estimates. Field staff consult with regional and national immunization and monitoring experts and gain valuable information about changes and events that could impact coverage (e.g., amount of vaccine available, changes in immunization policies, etc.) as well as insights into the functioning of national immunization systems and the quality of data they provide.
Given the importance of data to the creation and implementation of immunization campaigns that reach children at risk, UNICEF also advocates for improvements in national monitoring, and in monitoring at sub-national, local, and health-facility levels.
The guidelines that UNICEF and WHO follow - the Global Immunization Vision and Strategy (GIVS) - emphasize the need for improved monitoring of vaccine coverage and highlight the value of improved surveillance to measure the extent of death and illness that occur due to vaccine-preventable diseases.