Demand forecasting for routine immunization
What is demand forecasting?
The purpose of demand forecasting is to ensure the availability of an adequate supply of high quality vaccines. When a sudden increase or decrease of vaccine demand is expected, for example, during the introduction of new vaccines into the EPI, at the beginning and end of accelerated immunization activities and during outbreaks, forecasting the demand and coordinating the supply capacity at the global level in advance is critical. Furthermore, the availability of quality vaccine could affect the decision making process for disease control policies, especially when the global vaccine need is expected to exceed the global production capacity. It is essential that the demand growth rate be coordinated with scale-up activities of vaccine producers to avoid shortages. In particular, in times of disease outbreak response, the distribution of available resources must be well coordinated at the global level.
What is the situation today?
Dramatic fluctuations of the vaccine supply for routine immunization is not expected today. The immunization programme is fixed and the number of prequalified suppliers is stable and sufficient. Unless the coverage rate or wastage rate of routine immunization changes rapidly in countries with large populations, or if there is any sudden change in the target population, the demand for routine vaccines will not change beyond the capacity of manufacturers to respond.
Why must demand forecasting systems be closely monitored?
As the demand for routine vaccines is stable almost each year, one of the most commonly used methods to estimate the requirements for the following year is based on the amount of vaccine used in the previous year. Unfortunately, this widely used method does not detect chronic vaccine supply problems, such as poor storage practices, inefficient stock management, and inappropriate vial sizes, and allows these problems to be carried on from one year to the next. Using accurate estimates of vaccine needs will strengthen the country's vaccine supply infrastructure, helping them to increase efficiency and reduce expenditures.
WHO demand forecasting process
WHO will assist countries with demand forecasting for routine vaccination to help nations address supply problems and implement better national planning systems for their immunization programmes. Countries with large discrepancies between their calculated needs and actual purchase orders may, upon their request, be visited by WHO to identify the reasons for vaccine supply problems and help coordinate steps to be taken to address these problems. This process may include a review of the country's demand forecasting techniques, an assessment of discrepancies between the order made and doses given and assistance with other vaccine supply problems and review of measures to correct them. These experiences could be shared in workshops among countries, or through information sharing in meetings and publications.