# 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.

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.

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?

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?