5.1 Estimating vaccine needs
Vaccine management involves estimating the number of vaccine doses, diluents and injection equipment (e.g. syringes, needles) needed for a particular population over a stated supply period. In order to run an efficient and effective immunization session you need to have an adequate supply of vaccines of acceptable quality. This is essentially dependent on reliable planning and monitoring. You might have heard from mothers in the community that the health facility ran out of vaccines and their child could not be immunized. On the other hand, health facilities may have an excess stock of vaccine that has passed its expiry date and has to be thrown away. You should try to ensure that these situations do not arise in your Health Post (Figure 5.1).
Before we move on, remind yourself of the meaning of some key terms from previous study sessions.
What is the expiry date?
The expiry date is the (international calendar) date after which a vaccine, diluent or other consumable item should not be used for the purpose of immunization, because of possible loss of potency (vaccines; diluents) or durability (syringes, needles and other items).
Potency refers to the ‘strength’ or ‘effectiveness’ of a vaccine; durability refers to the time period that equipment such as syringes or needles remain in good condition (how long they last).
What is a diluent?
A diluent is a liquid used to reconstitute a freeze-dried vaccine. Each vaccine has its own diluent which should not be used to reconstitute any other vaccine.
Determining your vaccine needs accurately is important because it allows you to manage your immunization programme efficiently. Good vaccine management:
- enables you to use vaccines efficiently, and reduce wastage
- avoids shortages or excess accumulation of vaccines.
If the vaccine needs for your Health Post are not estimated correctly, and the wrong amounts are supplied by the health centre, this may result in shortage of vaccines or excess stock.
What is the problem if you order excess stock?
There is the risk that the vaccines will pass their expiry date before you need to use them, so they will be wasted.
We now consider how you can determine the vaccine needs for your Health Post. There are three methods based on:
- size of the target population for immunization
- previous vaccine consumption data
- size of the scheduled immunization sessions.
You will learn about each of these methods in the sections that follow. But you should note that vaccine requirements are likely to vary a lot from one kebele to another; the stocks required for your immunization programme may be very different from the examples used in this study session.