The basic principle behind vaccine development is to expose the body to a weakened or inactivated form of a pathogen, such as a virus or bacteria, in order to stimulate the immune system to produce antibodies that can protect against the pathogen. When the body encounters a vaccine, it mounts an immune response by producing antibodies and activating immune cells called T cells. These immune cells “remember” the pathogen, and if the body is later exposed to the actual pathogen, it can quickly produce the necessary antibodies and T cells to fight the infection.
There are several approaches to vaccine development, including:
- Live attenuated vaccines: These vaccines contain a live, weakened form of the pathogen. They are usually effective, but can have side effects in some people, such as those with compromised immune systems.
- Inactivated vaccines: These vaccines contain a killed version of the pathogen. They are generally safe, but may not provide as strong or long-lasting immunity as live attenuated vaccines.
- Subunit vaccines: These vaccines contain only a portion of the pathogen, such as a protein or carbohydrate. They are generally safe, but may not provide as strong or long-lasting immunity as live attenuated or inactivated vaccines.
- DNA vaccines: These vaccines contain a small piece of the pathogen’s genetic material, such as DNA or RNA. They are still in the experimental stage, but show promise as a safe and effective way to stimulate the immune system.
In the case of COVID-19, Indian vaccine manufacturers have adopted a variety of approaches to produce vaccines. For example, the Covishield vaccine, developed by the Serum Institute of India, is a licensed, inactivated vaccine that was developed using a modified version of the original SARS-CoV-2 virus. The Covaxin vaccine, developed by Bharat Biotech, is an inactivated vaccine that was developed using a strain of the SARS-CoV-2 virus that was isolated in India. Both vaccines have undergone clinical trials and have been approved for use in India.