5.5.1 Calculating quantities of vaccine for a particular supply period
The vaccine needs for a specific storage or supply period (in this case, 12 months or 48 working weeks) can be calculated using the following equation:
qperiod = (qyear ÷ 12) x psupply when the supply period is given in months, or qperiod = (qyear ÷ 48) x psupply when the supply period is given in working weeks. where:
- qperiod = vaccine needs for the period
- qyear = annual vaccine needs
- psupply = supply period (in months or weeks).
You can see an example of vaccine needs calculated in weeks in the following question.
If the number of doses of vaccine required for one year in an imaginary kebele is 2,000, how many doses would be needed for a two-week period?
In this example, the annual vaccine needs qyear = 2,000 and the supply period psupply is 2 weeks.
The vaccine needs for one week would be 2,000 doses ÷ 48 working weeks.
So the vaccine needs for the period (qperiod) of 2 weeks is (2,000 ÷ 48) x 2 = 83 doses.
Therefore, 83 doses would be required for a two-week period in this example.