Question

How are vaccines made? - Why do they take so long to make? - Why can't you just walk into Walgreens and buy a vaccine for Covid-19 yet?

Answer 1

Vaccines work by preparing the immune system to combat with infections and prevent diseases.

The production of vaccine starts with growing viruses or bacteria in a lab with proper management of parameters such as pH,oxygen rate, sterility and homogenicity. A slight variation in these parameters can affect the growth and cause delay in production process. Depending on the vaccine, cell cultures are grown in medium and it can take 2 days to 3months for the growth. From a small amount of culture, millions of vaccine doses can be made. Once culture is ready, the micro organisms are extracted from the culture through purification for eliminating any traces of the culture media. Then the micro organisms are inactivated from its ability to cause diseases. This inactivated micro organisms are called valence. A vaccine can include one or more valence to protect aganist one or more diseases, in the same shot. Special care should be taken to ensure the prevention of interaction of one valence with other. Usually utmost care is taken in this procedure and precise combination of valence takes years of scientific research and development. After this, stabilizers or preservatives are added for enabling vaccines to be stable, potent and effective. An adjuvant is also added to enhance the body's immune response to vaccine. Certain vaccines are freeze dried into powder and at time of administration these powder is mixed with diluent. After this vaccines are filled in vials or syringes and send for quality inspection and later for clinical trials.

Development of vaccines takes a long time because ample time is spend on identifying and studying the microorganisms by the scientists. Once a vaccine is produced, it should pass testing procedures and safety medical examinations. 70% of time required to produce vaccine is spend on quality controls. Only after this a vaccine can start for clinical trials in human. so vaccines takes about 6 months to 36 months to go through all these procedures and to be available for public.

The vaccine for covid19 is not yet ready. Covid 19 has mutated into 2 strains since its discovery which makes vaccine much harder to identify. Human trials on vaccine had started in US, which means that Covid vaccine are in its advancing stage. WHO predicts that covid vaccine will be ready by early 2021.