# Self-Assessment Questions (SAQs) for Study Session 5

## SAQ 5.1 (tests Learning Outcomes 5.1, 5.2 and 5.3)

Imagine that you are working in a *kebele* with a total population of 5,700, and that 5% of the total population are children aged 0 to 11 months. There is only one immunization site — your Health Post. You have been given a target of 90% immunization coverage for pentavalent vaccine for the year. The wastage rate has been agreed as 5%.

- Based on the national EPI schedule for this vaccine, calculate the annual pentavalent vaccine needs, based on the size of the target population in this
*kebele*.

### Answer

The equation for calculating the annual vaccine needs, based on the size of the target population, is:

- Annual vaccine needs = pt x dn x ic x wf where:

- pt is the target population – for pentavalent vaccine this is the number of children aged 0–11 months (calculated below)
- dn is the number of doses of vaccine in the recommended schedule — this is 3 for pentavalent vaccine
- ic is the target immunization coverage rate — in this example it is 90%
- wf is the wastage factor (calculated below)

The number of children aged between 0–11 months is 5% (0.05) of the total population of 5,700, which is:

- 5,700 x 0.05 = 285 children in this age group (5% expressed as a decimal number is 0.05)

The wastage factor is calculated from the wastage rate of 5% using the equation:

- Wastage factor (wf) = 100 ÷ (100 – % wastage rate)

So for a wastage rate of 5%:

- wf = 100 ÷ (100 – 5) = 100 ÷ 95 = 1.05

Using the equation below to calculate the annual vaccine needs based on the target population size:

- pt x dn x ic x wf = 285 x 3 x 0.9 x 1.05 = 808 doses

So the annual pentavalent vaccine needs, based on the size of the target population in this *kebele*, is 808 doses.

## SAQ 5.2 (tests Learning Outcomes 5.2)

Imagine that in your *kebele* you plan to deliver two sessions of immunization per week for 45 weeks of the year. Your Health Post is provided with PCV10 (Synflorix) vaccine in multi-dose vials of 2 doses per vial, and at each immunization session 5 vials are used.

- Estimate the annual PCV10 vaccine needs for the Health Post, based on the size of the immunization sessions.

### Answer

The equation for calculating annual vaccine needs based on the size of the immunization sessions is as follows:

- Annual vaccine needs = posts x weeks x sessions x vials x doses; where (for PCV10 vaccine in this example):

- posts is the number of immunization sites, which is 1
- weeks is how many weeks the immunization site operates, which is 45
- sessions is the number of sessions per week, which is 2
- vials is the number of vials used per session, which is 5
- doses is the number of doses per vial, which is 2.

So the annual vaccine needs for DPT in this example is:

- 1 x 45 x 2 x 5 x 2 = 900 doses.

## SAQ 5.3 (tests Learning Outcomes 5.1 and 5.3)

If the wastage rate for oral polio vaccine (OPV) is 10%, what wastage factor would you need to use when calculating the annual OPV needs, based on the size of the target population?

### Answer

The wastage factor is calculated from the wastage rate (expressed as a percentage), using the following equation:

- Wastage factor (wf) = 100 ÷ (100 – % wastage rate)

In this example, the wastage rate for OPV has been set at 10%. So the wastage factor is:

- wf = 100 ÷ (100 – 10) = 100 ÷ 90 = 1.11

Therefore, the wastage factor is 1.11.

## SAQ 5.4 (tests Learning Outcomes 5.1 and 5.4)

- a.How much PCV10 vaccine would be required by the Health Post mentioned in SAQ 5.2 for a 2-week period?
- b.What is the minimum stock level for PCV10 vaccine for a 2-week period for this Health Post?
- c.What is the maximum stock level for PCV10 vaccine in the same period?

### Answer

- a.In the example given in SAQ 5.2, there are two immunization sessions per week. Five multi-dose vials of PCV10 each containing 2 doses is used per session, so 20 doses are needed per week. Therefore the number of doses required for a 2-week supply period in this
*kebele*is 40 doses. - b.The minimum stock level is generally taken to be 25% (or 0.25) of the requirement for the supply period, which in this example is 2 weeks. The equation needed to calculate the minimum stock level for a 2-week period is:
- s
_{mini}= q_{period}x 0.25 (25% expressed as a decimal number is 0.25) - where q
_{period}is the number of doses required for the supply period, which in this example is 40 doses. - s
_{mini}= 40 x 0.25 = 10 doses. - So the minimum stock level for PCV10 vaccine for a 2-week period in this
*kebele*is 10 doses.

- s
- c. The maximum stock level for PCV10 for a 2-week period in this
*kebele*is calculated from the following equation:- s
_{maxi}= q_{period}+ s_{mini}s_{maxi}= 40 + 10 = 50 doses

- s
- d.So the maximum stock level for PCV10 vaccine for a 2-week period in this
*kebele*is 50 doses.

Summary of Study Session 5