Vaccines are produced in large scale as they need to be administered to large populations of children and adults to be effective as a public health tool. This large scale production is often a challenge.
Stages of vaccine production
Vaccine production has several stages. Process of vaccine manufacture has the following steps:
- Inactivation – This involves making of the antigen preparation
- Purification – The isolated antigen is purified
- Formulation – The purified antigen is combined with adjuvants, stabilizers and preservatives to form the final vaccine preparation.
Generating the antigen from the microbe
The initial production involves generation of the antigen from the microbe. For this the virus or microbe is grown either on primary cells such as chicken eggs (e.g. in influenza) or on cell lines or cultured human cells (e.g. Hepatitis A). Bacteria against which the vaccines are developed may be grown in bioreactors (e.g. Haemophilus influenzae type b). The antigen may also be a toxin or toxoid from the organism (e.g. Diphtheria or tetanus) or it may be part of the microorganism as well. Proteins or parts from the organism can be generated in yeast, bacteria, or cell cultures. Bacteria or viruses may be weakened using chemicals or heat to make the vaccine (e.g. polio vaccine).
Isolation of the antigens
After the antigen is generated, it is isolated from the cells used to generate it. For weakened or attenuated viruses no further purification may be required. Recombinant proteins need many operations involving ultrafiltration and column chromatography for purification before they are ready for administration.
Adjuvants, stabilizers and preservatives
Once the antigen is developed the vaccine is formulated by adding adjuvants, stabilizers, and preservatives. The role of the adjuvant is to enhance the immune response of the antigen. The stabilizers increase the storage life, and preservatives allow the use of multi dose vials.
It is difficult to develop and produce combination vaccines due to the possibility of incompatibilities and interactions among the antigens and other ingredients of the vaccines.
Vaccine Production Requirements
The product needs to be protected from air, water and human contamination. The environment needs to be protected from spillage of the antigens