Data are collected through the WHO UNICEF Joint Reporting Form. This form is sent out by both organizations to the Ministries of Health with expected completion by April 15 of each year.
The World Health Organization (WHO) and the United Nation’s Children’s Fund (UNICEF) compile country data series based on both types of data gathered through the WHO/UNICER Joint Reporting Form (JRF) on Vaccine-Preventable Diseases.
There are three types of data requested and collected through the JRF:
- Administrative coverage data.
Survey data (national surveys conducted by DHS, MICS, EPI Cluster or other valid instruments).
3. Official national estimate (the estimate of coverage that the Ministry of Health believes to be correct; which may or may not coincide with the administrative or national survey data).
- The number of doses administered as recorded by the health providers;
- The number of children in the target population, usually live births or infants surviving to the age of one year; and
- An estimate of completeness of reporting, e.g., percentage of districts in the country that reported their data.
For additional details, see:
The content of the Joint Reporting Form was developed through a consensus process by staff from UNICEF, WHO and selected ministries of health. Data collected in the Joint Reporting Form constitute the major source of information on estimates of national immunization coverage, reported cases of vaccine-preventable diseases (VPDs), and immunization schedules, as well as indicators of immunization system performances.
Surveys are frequently used in conjunction with administrative data; in other instances they constitute the sole source of information on immunization coverage levels. The principle types of surveys are the Expanded Programme on Immunization (EPI) 30–cluster survey, the Multiple Indicator Cluster Survey (MICS), and the Demographic and Health Survey (DHS).
EPI 30–cluster surveys are frequently conducted by national EPI staff, are designed specifically for measuring immunization coverage, are simple to administer and easy to conduct, but have a precision plus or minus 10% points at 50% coverage. The MICS and DHS are more extensive surveys covering a variety of indicators, have a more rigorous design, and typically have a higher degree of precision, but are more expensive, logistically more complex and the questionnaire is longer and more difficult to administer.
Draft reports produced by the WHO UNICEF working group are sent to each country for review, comment, contribution and final approval.
Country correspondence adjustments are made to the estimates with consultation to the WHO UNICEF working group upon which final reports are completed. This collaboration prior to the public release of the final estimates is important not only to inform national authorities of the results of the review before its general release, but also to take advantage of local expertise and knowledge. The consultations with local experts attempt to put the data in the context of local events, both those occurring in the immunization system (e.g. vaccine shortage for parts of the year, donor withdrawal, etc.) and more widely occurring events (e.g. international incidences, civil unrest, heightened political commitment to immunization, etc.).
As mentioned previously, there are no adjustments made to reported data in cases where data for a country was available from a single source, usually the national reports to WHO. There is also no attempt to group countries based on income, development levels, population size or geographic location. The resulting estimates are based only on data from that country.
Immunization coverage levels vary over time, and while there are frequently general trends, there is attempt to fit the data points to curve using smoothing techniques.