A vaccine is a product of biological origin that is used to provide acquired immunity against an infectious disease. Vaccines typically resemble the disease-causing microorganism and are derived from a weakened/killed form of the microorganism, its toxins, or its surface proteins.
There are several steps involved in the making of a vaccine:
- Production starts with growing the microorganism(bacteria/virus) in the lab in cell cultures. During this process, it is important to maintain temperature, pH, oxygen rate, sterility, and homogeneity of the cell cultures. This process can take from 2 days to 3 months, depending on the microorganism being cultured. Even a small culture can lead to the production of millions of vaccine doses. The main purpose of this step is to develop the antigens present on the microbial surface.
- The next step is harvesting where the antigens produced from microorganisms are extracted.
- This is followed by purification. Here, impurities are removed through various physical and chemical methods. This is done to eliminate any traces of culture media.
- Then, inactivation is done on the microorganism to eliminate its pathogenicity. However, its ability to cause a precautionary immune response from the body is retained. This inactivated microbe is called a Valence.
- Then, valence assembly takes place where all the antigenic substances are combined into a single component.
- The next step is formulation where all the ingredients are melted together. A vaccine can contain one or more valences and each valence must remain fully effective and shouldn’t interfere with other valances. Stabilizers and preservatives are added to ensure that the vaccine remains stable, potent, and effective.
- Then, the vaccine is filled into a syringe or vial. The vaccine can be freeze-dried into a powder to preserve it further by removing the excess water. When the vaccine needs to be administered, it is reconstituted by combining the powder with a diluent. After this, each vial/syringe undergoes visual inspection by human eyes and state-of-the-art surveillance technology.
- The vaccine is then labeled according to the regulatory requirements and then packaged for shipping. Quality assurance confirms that the product has been manufactured and tested in accordance with the correct procedures. If a batch does not meet the quality criteria, it will be destroyed.
- Finally, when the vaccines are being shipped, they must be stored at a temperature between 2oC and 8oC at all times as they are very sensitive to temperature fluctuations.
These vaccines are then distributed all over the world.