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How vaccines are developed

Published Apr 24, 2020


DURBAN - There are at least 92 vaccines under development for the Coronavirus (Covid-19). On Thursday Britain begun testing of an experimental Covid-19 vaccine,

the latest in a cluster of early-stage studies in search of protection against the coronavirus.

In the race to create a vaccine for the Covid-19, some researchers are testing new approaches they hope can ultimately produce vaccines in months rather than years.

Vaccines are made using weakened or dead parts of a virus or germ. When the weakened germ is injected into your body, it mimics an infection without causing an illness.

Your immune system produces cells that remember the virus and how to respond to it later, providing you immunity.

However, health experts say it's the clinical development stage that takes the most time.

Clinical development is typically divided into three phases which are each done through testing on humans.

Dr. Sarah Gilbert, professor of vaccinology at the Jenner Institute, and her team took only three months to design the vaccine said, "I have a high degree of confidence in this vaccine. Of course, we have to test it and get data from humans. We have to demonstrate it works and stops people from getting infected with coronavirus before using the vaccine in the wider population.”

The first phase, tests a vaccine on a small group of people to see whether the vaccine is safe. The second phase is tested on hundreds of people so researchers can learn more about the body’s immune response to the vaccine. The third phase is tested on thousands of people so researchers can further determine the vaccine’s efficacy and safety.

Dozens of vaccine candidates are in various stages of development around the world. Experts have cautioned that even if early studies go well, it will be at least a year before any are available for widespread use.

Once it is determined how the virus and bacteria will be modified, vaccines are created through a general three-step process:

Antigen (a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies) is generated. Viruses are grown in primary cells (i.e. chicken eggs for the influenza vaccine), or on continuous cell lines (i.e. human cultured cells for hepatitis b vaccine); bacteria is grown in bioreactors (i.e. Hib vaccine).

Antigen is isolated from the cells used to create it.

Vaccine is made by adding adjuvant, stabilizers and preservatives. Adjuvants increase immune response of the antigen; stabilizers increase the vaccine’s storage life; and preservatives allow for the use of multi-dose vials.

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