How do the specific vaccines work?
As with all vaccines, the injected solution contains information that directs your immune system to make antibodies against a critical part of a virus or bacteria. Its Achilles’ Heel. In the case of SARS-CoV2 it is its spike protein. The virus uses this protein to attach to your cell before entering it, which is critical to its life cycle. In addition, the vaccines also instruct your body to make memory cells (T-cells) that remember this foreign substance. Thus, insuring that when you see this same protein in the future, your immune system promptly takes the appropriate steps to protect you against the pathogen.
The difference in vaccines is how these instructions are conveyed to your immune system.The following is a review of the currently approved Emergency Use Authorization (EUA) vaccines & how they direct your immune system.
There are several types of Covid-19 vaccines:
1) mRNA Vaccines (Pfizer & Moderna).
These vaccines contain an instruction (mRNA) which consists of a series of nucleotides that enter your cell. These nucleotides code for amino acids that combine to make a critical part of the virus, the spike protein.
This protein provides the means by which the virus attaches to your cells and is therefore critical to its life cycle. When released from your cell, your immune system recognizes this protein as foreign and makes an antibody against it. Should you contract the infection, your antibodies immediately attach to the spike protein (like a key in a lock) and prevent the virus from attaching to your cell. The immune response invoked by the vaccine also activates T cells that serve as memory cells to prepare your system for the next time it sees the spike protein.
2) Viral Vector Vaccines (Johnson & Johnson and Astra Zeneca/Oxford)
Like the mRNA vaccines, this group gets the instructions for the manufacture of the spike protein into your cell but via a harmless virus (adenovirus). As before, your immune system sees this as a foreign protein & makes an antibody against it. The only difference between these vaccines is that they use different virus vectors.
3) Recombinant Protein (Novavax)
This vaccine involves the manufacture of the entire spike protein and combining them into a small (nano) particle which resembles the virus but without its body (RNA). This is combined with an adjuvant which enhances the immune response. This mixture is the vaccine that is injected. Again, the body sees the protein as foreign and makes an antibody against it.
However, there is a potential problem! The immune system is very specific for the same reason that the key to your house will not open you neighbor’s home and vice versa. The protein (spike in this case) that your body encounters during an infection has to be identical to the protein that produced the initial immune response. So, the lock (viral protein) has to be a perfect match for the key (antibody) that was made for it. Mutations and the variants that arise from them, change the “lock” (spike protein) so the “key” (antibody) derived from the vaccine, is less likely to work or in some cases doesn’t work at all (for example the AstraZeneca/Oxford vaccine vs the S African variant). This will necessitate a reformulation of the vaccine (booster), possibly yearly as is done with the flu vaccine, to accommodate these changes in the spike protein. The good news is that this can easily be done with the mRNA vaccines. I assume that it can be done with the others, but I have not heard how difficult this will be.