Finally, I have been able to put up the post on Covid-19 Vaccine, yes the SARS-CoV 2 virus vaccine and I will be discussing the Vaccines you are familiar with. I will be discussing the Pfizer /BioNTech, Moderna, and AstraZeneca vaccines.
For the Vaccines to receive FDA emergency use authorization, the vaccines need to meet safety (where side effects are not serious or deadly), Efficacy (the ability of the vaccine to prevent disease or infection), and the efficacy of the vaccine goes to preventing against disease and preventing Asymptomatic disease. The FDA vaccine phase includes the preclinical phase and this phase, is basically animal testing with the vaccine. If the animal testing in the preclinical phase is successful, then the next phase is the human trial of small population size. after which a larger size of the human population is tried. This is called the clinical phase and it has three sub-phases that all involve human populations that become larger as each phase passes. When all safety goals are met, it gets FDA approval and there will still be follow-up studies on the drug. During the preclinical phase, the vaccine is given to animals that have almost the same genomic level as humans such as Mice. when the vaccines are tested on these animals, they are checked for side effects, and/or death. During this test, the efficacy of the vaccine is tested on the animal, by injecting the animal with the virus after giving them the vaccine. If the vaccine has a efficacy with no lethal or serious side effect, then the drug can move to clinical testing where the three phases of human testing occur., , .
In the clinical stage with phase one, the vaccine is given to humans in a small sample population size. It should be less than a 100 participant with the intent of making them well. During this testing, side-effects are checked, and the patients are properly checked so there are no comodity as a result of using the vaccine but while checking for side effects, they can range from chills, rash, nausea, seizure and in worst case scenario death. In this stage, since it is the first time it is injected int humans, the dosage (the upper limit and the lower limit) are identified., , In the second stage of clinical testing, a larger population compared to the phase 1, and in this phase, the participant can range from a 100 to about 1000 people. In this case, people of different demographics are added, side effects are monitored, and people from different age ranges are tested upon. Also in stage 2, the effectiveness of the dosage determined in phase 1 is checked and confirmed. Phase3 is the phase where the vaccines on a larger size of about 1000 to about 100 thousand. The patient being tested upon should be healthy, not have underlying disease and should be from several demography. This patients are allowed to perform their daily activity after which they are checked for side effect, or got the disease. This would include the controlled group. In the case of covid-19, it was an emergency case, and so there was an emergency use approval.,
Moderna and Pfizer uses the mRNA technology for their vaccine. The lipid nanoparticle of the mRNA which is a phospholipid biolayer is taken along with the mRNA which was taken from the SARS-CoV2 virus. Remember that in my previous posts I mentioned the Spike Protein (S-Protein) being the virulent organelle of the virus responsible for entering the host. With the vaccine, the mRNA that is needed to code for the S-protein is found. The mRNA is then inserted into the lipid nanoparticle. The mRNA gets into the cell through fusing and uses the cell's Ribosome to create proteins (translation) where the proteins (MHC2, and MHC1) are expressed on the cell membrane. The MHC1 proteins are found in all nucleated cell, while the MHC2 are found on macrophages, dendritic cells, and lymphocytes. The MHC2 and and the T-helper cell interact using a CD4 protein to cause the release of cytokines (interleukin 2, interleukin 4,) as a result of the activation of the T-helper cells which allows the B-cells to proliferate and differentiate into plasma cells which starts to make the antibodies that work against the S-protein of the actual SARS-CoV2 virus., , ,
Astrazeneca vaccine doesn't use mRNA, rather uses the chimpanzee adenovirus which poccesses a DNA that releases a protein similar to the S-protein of the SARS-CoV2. The S-peptide is released into the body where it is converted into mRNA, then to DNA then into the DNA of the chimpanzee adenovirus so as to create an immune response to the virus. The DNA is released into the host cell cytoplasm where it goes to the nucleus. It does not go into the DNA but rather uses the host cell to convert the DNA to mRNA which is then goes into the cytoplasm to interact with ribosomes to create proteins which are then expressed in the cytopolasm, thereby generating immune response where B cells are changed into plasma cells that generates antibodies that are generated against the virus S-protein. ,
Currently, these vaccines are given in two shots and vaccines are being modified to attack the new strains of the virus that have mutated over time.
Image References
Image 1 || Flickr || Pfizer COVID-19 vaccine
Image 2 || Flickr || AstraZeneca introduces new safe vaccine at preventing coronavirus infection