Step 1: Understanding the virus
Researchers first identify the surface molecules like proteins or sugars which are used by the viruses to first contact the human cells. These molecules are then analyzed for if they can be used to produce an immune response. This is not possible unless the genetic sequence of the virus must be known. This enables the development of testing kits and development of therapeutic options.
Step 2: Identifying candidates for vaccine
Vaccine candidates can be identified using various strategies like
a) Weakening the virus- With this strategy the virus is introduced into a human body in a weak form, so that it can replicate enough to induce immune response (memory B cells) but not enough to cause a disease. This way our bodyguard (memory B cells) will remember the virus and would be prepared to fight against it, whenever they encounter it in the future. Many vaccines in the past have been made using his method, for example measles, mumps, rubella etc. This vaccine however can not be given to people with low immunity but only 1 or 2 doses can make the person immune.
b) Inactivating the virus- In this strategy the virus is chemically inactivated so that it cannot reproduce inside the human body but since the virus is recognized as a foreign particle, an immune response is induced. This vaccine can be given to everybody but needs to be given several times to be effective. Examples include Hepatitis B, Rabies, inactivated polio vaccines etc.
c) Using parts of virus- Here only a single part of virus is used to simulate the immune response. This may include one of it protein from the virus or simply the genetic material such as DNA or RNA, which may be used to produce recombinant proteins. These proteins are alien to human body and help elicit the immune response. Examples of vaccines developed via this method are the hepatitis B and the human papillomavirus (HPV)vaccines. This vaccine works for all the people and is effective with only 2 doses. For the same purpose Genaxxon supplies: https://www.genaxxon.com/sars-cov-2. Don’t forget to check out!
With all the information human kind acquired in the past regarding vaccine development also helps researchers to identify vaccine candidates and speeds up the process. They likely can already estimate the number of doses required to achieve the immunity. Rules and regulations have been set to test the relevance of the vaccine and control the process involved in its manufacture, production and clinical trials.
Step 3: Pre-clinical testing
These trials are carried out in animals, to check the response; a vaccine might have on humans. This is a crucial part of vaccine development, as in this step the effectiveness of the vaccine is analyzed.
Step 4: Clinical trials
These are the trials which are conducted in order to achieve safety and efficacy data of a new vaccine. This ensures scientific validity and result reproducibility. Only 10% of the drugs going in the clinical trials get approvals and it may cost billion of dollars per approved drugs. These trials have 4 phases:
a) Phase 0: This phase is optional and is usually conducted with 10-15 people. This phase produces data related to pharmacodynamics and pharmacokinetics. This trial documents the absorption, distribution, metabolization, and removal (excretion) of the drug, and the drug's interactions within the body, to confirm that these appear to be as expected.
b) Phase 1: This phase is conducted with 20-80 volunteers and is done to screen the vaccine for any side effects.
c) Phase 2: This phase is conducted to estimate the preliminary efficacy of the drug in a "treatment group (the individuals with disease for which the vaccine is under trial)", usually against a placebo control group (healthy individuals with no disease). It involves a dozen to nearly 100 infected individuals.
d) Phase 3: This phase is carried outfor the vaccine’s final confirmation of safety and efficacy. This is carried out with large group of people which may range from 1000- 3000.
e) Phase 4: Safety studies during sales are the post marketing studies to address the risks, benefits, and optimal use of the vaccine and go on for its lifetime of medical use. As such, they are ongoing during the drug's lifetime of active medical use.
Step 5: Regulations of vaccine development, manufacture and distribution
Regulatory issues are involved in nearly every aspect of vaccine development, manufacturing, and marketing approval. Regulations come into play from the time of vaccine design and clinical testing, through manufacturing, to when the final product is distributed for widespread use.
Step 6: Production
Once the vaccine passes all the trials and regulations on small scale, it requires substantial manufacturing capability, human resources and equipments to carry out large scale production. All the processes are carefully monitored and quality is controlled at all levels. Internal and external audits are conducted to keep the quality in check.
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Source:
2) https://www.ncbi.nlm.nih.gov/books/NBK236432/
3) https://www.chop.edu/centers-programs/vaccine-education-center/making-vaccines/how-are-vaccines-made
