Title: Calculating numbers in the target population
Course: Immunization - Ethiopia (Full)

Calculating numbers in the target population

Table 5.1 shows an estimate of the target population for immunization in a kebele with a total population of 5,000. A figure of 4% of the Ethiopian population is usually taken to estimate the coverage required for all live births and surviving infants. You can assume that (on average) about 23% of the Ethiopian population will be women of childbearing age, of whom about 4% will be pregnant in a typical year.

Table 5.1  Estimating the target population (pt) for immunization in a kebele with a total population of 5,000.

Category | % of total population | Estimated number in target population
Live births | 3.6 | 180
Surviving infants | 3.4 | 170
Women of childbearing age (pregnant and non-pregnant) | 23 | 1,150

You estimate the target population by multiplying the total population by the percentage in a particular category; for example in Table 5.1:

Expressing a percentage as a decimal number is easy, e.g. 90% is the same as 0.9; 23% is the same as 0.23, and 4% is the same as 0.04.

- The estimated number of women eligible for TT vaccination (Figure 5.3) is 5,000 x 23% (or 0.23) = 1,150
- The estimated number of children eligible for all other EPI vaccines is 5,000 x 4% (or 0.04) = 200, if you take the simple average of 4%. If you use the Ministry of Health indicators of live births (3.6%) and surviving infants (3.4%), the numbers will be 170 and 180 respectively.

Figure 5.3  About 23% of the Ethiopian population are women of childbearing age (pregnant and non-pregnant combined). (Photo: Ali Wyllie)

Look back at Figure 5.2. What was the estimated target population eligible for TT immunization in Fura kebele in the year shown?

Show answer

The estimated eligible population for TT vaccination was 1,478 women of childbearing age (247 pregnant and 1,231 non-pregnant) in Fura that year; this is 23% of the total population of 6,348 in the kebele.