Data Notes
1. Guidelines for monitoring coverage of vitamin A supplements
Guidelines of the Global Alliance for Vitamin A (GAVA) provide advice and information to district-level managers and national-level managers on national-level monitoring and reporting of vitamin A supplementation programs for children 6 to 59 months.
2. Process for the UNICEF Global VAS Coverage Database
Since 2000, UNICEF has estimated VAS coverage in priority countries1 at national, regional and global levels as part of organization-wide efforts to monitor the situation of the world’s children. A report which describes the process, rules and assumptions applied to administrative data received annually from country teams for the generation of the UNICEF Global VAS Coverage Database, was published in March 2020. The report includes a flowchart that provides a quick overview of the overall review process. as well as a detailed account of the exam questions, the different scenarios encountered and how each is approached. Summaries of 2.1. Indicators for the UNICEF Global VAS Coverage Database; and 2.2. The process for generating annual national VAS coverage estimates for the database is provided below with full details available in the report.
2.1. Indicators from the UNICEF Global VAS Coverage Database
Table 1. Indicator definitions for vitamin A supplementation coverage in the UNICEF global database
| Indicator name | Definition of the indicator | Numerator | Denominator |
| VAS coverage 1 semester 1 (January to June) | Percentage of children aged 6 to 59 months who received an age-appropriate dose of vitamin A in the first semester through the primary delivery mechanism* | Number of children aged 6 to 59 months who received an age-appropriate dose of vitamin A through the primary delivery mechanism* during the first half of the year | Total population of children aged 6 to 59 months |
| VAS coverage for 2 semester 2 (July to December)
|
Percentage of children aged 6 to 59 months who received an age-appropriate dose of vitamin A during the second semester via the primary delivery mechanism* | Number of children aged 6 to 59 months who received an age-appropriate dose of vitamin A through the primary delivery mechanism* during semester 2 | Total population of children aged 6 to 59 months |
| 3. Annual coverage of the EVA in two doses (takes into account semesters 1 and 2) | Semester in which VAS coverage is lowest for children aged 6 to 59 months in a given calendar year. | Number of children aged 6 to 59 months who received an age-appropriate dose of vitamin A via the primary delivery mechanism* in the semester with the lowest coverage of the calendar year | Total population of children aged 6 to 59 months used to estimate coverage for the semester with the lowest coverage value for the calendar year |
*Defined as the mechanism that achieved the highest coverage during the semester.
Two-dose VAS coverage is the primary indicator for global monitoring of VAS programs. Two-dose VAS coverage is an estimate of the percentage of children aged 6 to 59 months who received two doses of VAS spaced approximately 4 to 6 months apart during a calendar year. The semester that reached less coverage between semester 1 and semester 2, is used as an approximation (for example, if semester 1 achieved 98 percent coverage and semester 2 achieved 50 percent coverage, two-dose coverage is reported as 50 percent). In cases where data only exists for one of the two annual semesters (i.e. the other semester did not have any data or did not have an approved coverage estimate) , two-dose coverage is reported as “no data.” In cases where more than 8 months have occurred between the semester 1 and semester 2 event, the two-dose coverage is 0 percent.
Although international recommendations call for vitamin A supplementation every four to six months, current surveillance efforts fail to determine the proportion of covered children who receive the two annual doses of vitamin A with appropriate spacing. The two-dose coverage approximations reported by UNICEF assume that in countries providing more than one cycle of supplementation, the same children are likely excluded from both distributions. The assumption is that the proportion of children reached by one campaign but not the other would be minimal. Therefore, the lower of the two coverage data points in a given year is assumed to be approximately equivalent to the proportion of children receiving two correctly spaced doses of vitamin A. There is a need to develop more refined methods to measure the proportion of children who are fully protected. .
2.2. Process for generating annual VAS coverage estimates for the database
National teams are asked to complete a standardized form for the annual VAS coverage report. The processes, standards and assumptions used to generate national coverage estimates based on data submitted by country teams are summarized in a organizational chart. The specific steps outlined in the flowchart from the point of data submission to the determination of the final estimate of national coverage for each semester are described in the report. This includes the questions asked in the exam, the different scenarios encountered, and how different challenges are approached.
(1) The UNICEF Global VAS Coverage Database 2000-2017 includes 82 countries identified as “priority” for national VAS programming from the year 2000. The list was based on a data-driven exercise undertaken in 2014 , using estimates of health and nutrition indicators around 2000, when VAS programs were generally launched. The two main indicators taken into account in this exercise were (i) the under-five mortality rate and (ii) the prevalence of VAD. In light of this analysis, the set of countries for which biannual and annual estimates of two-dose VAS coverage are reported in the UNICEF global database was limited to these countries. This list has been reduced to 64 priority countries as of the 2018 reference year. Countries requiring only subnational programs are not included in the database. Country lists can be viewed on this webpage under “Access data”.
