What is mRNA vaccine and how does it work?

Moderna announced results of human trials on the vaccine it has developed with US National Institutes of Health days after Pfizer had released trial results showing 90 per cent effectiveness in its own vaccine.

Both Pfizer and Moderna are testing their separate vaccine candidates that use messenger RNA, or mRNA, to trigger the immune system to produce protective antibodies without using actual bits of the virus.

If an mRNA vaccine was approved for coronavirus, it would be the first of its type. It’s a very unique way of making a vaccine and, so far, no such vaccine has been licenced for infectious disease

Once injected into the body, it 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.

According to horizon, mRNA vaccines trick the body into producing some of the viral proteins itself. They work by using mRNA, or messenger RNA, which is the molecule that essentially puts DNA instructions into action.Inside a cell, mRNA is used as a template to build a protein.

To produce an mRNA vaccine, scientists produce a synthetic version of the mRNA that a virus uses to build its infectious proteins.

This mRNA is delivered into the human body, whose cells read it as instructions to build that viral protein, and therefore create some of the virus’s molecules themselves. These proteins are solitary, so they do not assemble to form a virus.

The immune system then detects these viral proteins and starts to produce a defensive response to them.

Also, mRNA vaccines cut out some of the manufacturing process and should be easier and quicker to produce than traditional vaccines as they trigger the human body to produce the viral proteins itself.

There are two parts to our immune system: innate (the defences we’re born with) and acquired (which we develop as we come into contact with pathogens). Classical vaccine molecules usually only work with the acquired immune system and the innate immune system is activated by another ingredient, called an adjuvant. Interestingly, mRNA in vaccines could also trigger the innate immune system, providing an extra layer of defence without the need to add adjuvants.