How mRNA Vaccines works against COVID-19 - Moderna / Pfizer
Channel: MedicoVisual - Visual Medical Lectures
Date: 2020-03-06

Moderna has released the first batch of SARS-CoV-2 Vaccine for phase 1 trial.
Before a drug (and vaccine) is launched and marketed public use, it has to undergo rigorous testing.
Initially there is a pre-clinical phase in which tests are conducted in laboratory and on animals. After the drug is developed first it is tested on a small number of volunteers (20-100), in phase I trial, then gradually tested on larger population. i.e. 100-300 in phase II and 300-3000 in phase III. During these phases, the people who are given these drugs are carefully monitored for the development of any adverse effects. And if a drug passes all these phases only then it is made available in markets. [Reference: Katzung Review]
So currently this vaccine would be in phase I and it may take up to a year or so before it would be available for the general public.
The interesting thing about this vaccine is that it is the mRNA vaccine (unlike the traditional vaccines which are usually protein based; contain viral proteins or live attenuated [weakened] virus).
mRNA as you know contains the codon or message for protein synthesis. That’s why they are called messenger RNAs. So, this vaccine, that is by the way named, mRNA-1273, is the messenger RNA that codes for the stable unfused S-protein of coronavirus. I mean the S-Protein before it fuses with cell.
coronavirus attaches with the ACE2 Receptors of type II alveolar pneumocytes. This attachment of coronavirus with ACE2 causes a conformational change in this S-protein which leads to the fusion of envelope of the virus with the plasma membrane of the host cell.
Today we will briefly talk about how this vaccine will work.
When this vaccine that is mRNA of S-protein, is given to a healthy non-infected person via Intramuscular injection in the deltoid muscle, it will go into interstitial space, the space between muscle cells. This vaccine is actually an encapsulated lipid nanoparticle with mRNA inside it. This very small lipid-based particle can cross the cell membrane and will release the mRNA inside the cell. Why we need this Lipid nanoparticle? Because outside the cell (in extracellular environment) are the hostile RNAses that will quickly destroy the mRNA. And mRNA by itself cannot cross the cell membrane. So, this nanoparticle will be used as delivery vehicle to safely transport mRNA into the cell.
We will see how mRNA vaccine work
What is the role of Cytotoxic T cells, B lymphocytes and Helper T cells.
How mRNA vaccine are better than Traditional vaccines 

Website: https://www.medicovisual.com
Email: draizaz@medicovisual.com