THE FOUR MAIN TYPES OF COVID-19 VACCINE AND HOW THEY WORk
By: Dr. Emanuel Pieris
As I mentioned before getting vaccinated is one of many steps you can take to protect yourself and others from COVID-19. When Coronavirus, enters our body, our immune system recognises it as harmful and will trigger a response to fight off infection by creating antibodies. Unfortunately, the immune system does not always win this initial battle against coronavirus and many become very ill or in extreme cases die. A vaccine would provide protection by training our immune system to fight the virus.
Currently, there are four main types of COVID-19 vaccines. Below is a description of how each type of vaccine prompts our bodies to recognize and protect us from the virus that causes COVID-19. None of these vaccines can give you COVID-19. They are produced so that some of them try to smuggle the antigen into the body, others use the body’s own cells to make the viral antigen. It is rather difficult for me to explain this in a simpler way. Hope that you understand at least the main principles of how these vaccines work.
1.Inactivated whole virus vaccines use viruses whose genetic material has been destroyed so they cannot replicate, but can still trigger an immune response. Inactivated whole virus Covid -19 vaccine include Sinopharm,(BBIBP-CorV) and Sinovac (CoronaVAC) both from China as well as Bharat Biotech (Covaxin) from India. Requires 2 doses. The whole virus vaccine uses a weakened or deactivated form of the pathogen that causes COVID-19 to trigger protective immunity to it.
2.Nucleic acid vaccines use genetic material to provide cells with instructions to make the antigen. In the case of COVID-19, this is usually the viral spike protein. Once this genetic material gets into human cells, it uses our cells' protein factories to make the antigen that will trigger an immune response.mRNA vaccine gives our cells instructions for how to make a harmless spike protein that is unique to the virus. Our bodies recognize that the protein should not be there and build T-lymphocytes and B-lymphocytes that will remember how to fight the virus that causes COVID-19. mRNA vaccines include Pfizer-BioNTech, and Moderna produced in the USA requires 2 doses. Once injected into the body, the mRNA instructs the cells to produce antigens specifically the virus’ spike protein. which are then detected by immune cells, triggering a response by the body’s immune system.
3. Protein Subunit vaccines include harmless pieces (proteins) of the virus that cause COVID-19 instead of the entire germ. Once vaccinated, our immune system recognizes that the proteins don’t belong in the body and begins making T-lymphocytes and antibodies. If we are ever infected in the future, memory cells will recognize and fight the virus. Such Protin subunit vaccine is Nuovavax(NVX-CoV2373) The USA Maryland-based company Novavax has developed this protein-based coronavirus vaccine called NVX-CoV2373 requires also 2 doses, Protein subunit vaccine contains purified “pieces” of a pathogen rather than the whole pathogen to trigger an immune response.
4.Non-replicating Viral vector vaccines also work by giving cells genetic instructions to produce antigens. They use a harmless virus, different from the one the vaccine is targeting, to deliver these instructions into the cell. It contains a weakened version of a live virus, a different virus than the one that causes COVID-19 that has genetic material from the virus that causes COVID-19 inserted in it (this is called a viral vector). Once the viral vector is inside our cells, the genetic material gives cells instructions to make a protein that is unique to the virus that causes COVID-19. Using these instructions, our cells make copies of the protein. This prompts our bodies to build T-lymphocytes and B-lymphocytes that will remember how to fight that virus if we are infected. Oxford-AstraZeneca UK, Sputnik V or GAM-Covid-Vac (Gamaleya Research Institute) Russia and Johnson &Johnson (JNJ-78436735, Ad26.COV2.5) the USA. The number of doses required is 2 doses, This type of vaccine introduces a safe, modified version of the virus – known as “the vector” – to deliver genetic code for the antigen.
In a COVID-19 vaccine, the “vector” is the spike proteins found on the surface of the coronavirus.
The COVID-19 pandemic has devastated lives and livelihoods around the world. Vaccines are one of our most powerful tools against this infectious disease. The WHO recommends that priority be given to health workers at high risk of exposure and people aged 65 or older, followed by people with underlying comorbidities such as respiratory disease or diabetes. Thereafter the younger generation is in turn to receive the vaccine.
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