Explained: What is mRNA vaccine?

Description

Context: Moderna announced results of human trials on the vaccine it has developed with US National Institutes of Health.

The trials found the vaccine 94.5 per cent effective, and the announcement comes days after Pfizer had released trial results showing 90 per cent effectiveness in its own vaccine, developed in collaboration with BioNTech-Fosun Pharma.
The Moderna and Pfizer vaccines use the same technology, based on messenger RNA, or mRNA. Such vaccines make use of the messenger RNA molecules that tell the body’s cells what proteins to build.

Unlike a normal vaccine, RNA vaccines work by introducing an mRNA sequence (the molecule which tells cells what to build) which is coded for a disease specific antigen, once produced within the body, the antigen is recognised by the immune system, preparing it to fight the real thing
RNA vaccines are faster and cheaper to produce than traditional vaccines, and a RNA based vaccine is also safer for the patient, as they are not produced using infectious elements
Production of RNA vaccines is laboratory based, and the process could be standardised and scaled, allowing quick responses to large outbreaks and epidemics
Most current research is into RNA vaccines for infectious diseases and cancer, for which there are several early-stage clinical trials, there is also some early research into the potential of RNA vaccines for allergies
The mRNA, in this case, is coded to tell the cells to recreate the spike protein of the coronavirus SARS-CoV-2, which causes Covid-19.
It is the spike protein — which appears as spikes on the surface of the coronavirus — that initiates the process of infection; it allows the virus to penetrate cells, after which it goes on to replicate.
A coronavirus vaccine based on mRNA, once injected into the body, will instruct the body’s cells to create copies of the spike protein.
In turn, this is expected to prompt the immune cells to create antibodies to fight it.
These antibodies will remain in the blood and fight the real virus if and when it infects the human body.
Other types of vaccine include the non-replicating viral vector category, an example of which is the vaccine developed by Oxford and AstraZeneca.