Vaccine procurement and lot release
There are only about 30 different vaccine types (but many more product formulations) compared with approximately 20,000 drugs.55 Accordingly, there are relatively few vaccine manufacturers and a limited number of countries where vaccines are produced. Most countries use vaccines that are imported from elsewhere.
To support countries with limited national regulatory (NRA) capacity, WHO provides a system of vaccine prequalification that has been adopted as a standard for procurement by United Nations agencies and some countries. Alternatively, countries can procure their vaccines directly on the domestic or international market.
Regardless of how a country obtains vaccines, NRAs are responsible for licensing them, i.e. approving their use, within the country. Appropriate licensing of vaccines ensures that quality products are used in immunization programmes by determining that the manufacturer can provide a safe and effective vaccine.
Because vaccines are biological products and quality can vary from lot to lot, NRAs should conduct tests before a vaccine lot is released for public use. NRAs often delegate testing to a national control laboratory. NRAs are not responsible for testing vaccine lots when the vaccine is procured through a United Nations organization i.e. is prequalified, which takes responsibility for the testing.
Testing of every batch is not done for other drug products. The lot release system is perhaps the greatest difference between the NRA vaccine functions and NRA functions for other medicines.
Once the NRA releases a vaccine lot, the national immunization programme (NIP) takes responsibility for its proper storage and handling until it can be administered safely to the target population. Storage and handling, including maintenance of the cold chain (continuous refrigeration) involves many steps, and presents opportunities for immunization errors that could result in AEFIs.
Unlike other drugs, NRAs should test every vaccine lot before public use, unless this is done by WHO on behalf of United Nations agencies or producing countries. The system of lot release is probably the greatest difference between vaccines and other medicines.
Once the NRA releases a vaccine lot, the responsibility to keep the vaccine safe and effective is passed to the NIP.