What is mRNA vaccine and how is it different from traditional vaccine?

A vaccine typically contains an agent that resembles a disease-causing microorganism that stimulates the body's immune system to recognize the agent as a threat, and prompts it to destroy it. The vaccine further recognizes and destroys any of the microorganisms associated with that agent that it may encounter in the future.

On the other hand an RNA (Ribonucleic acid) vaccine also called as mRNA (messenger RNA) vaccine is a new type of vaccine that transfers molecules of synthetic RNA into human cells. Once inside the cells, the RNA functions as mRNA, reprogramming the cells to make the foreign protein that would normally be produced by the pathogen like a virus. In other words mRNA can deliver the genetic information to produce proteins within living cell tissue that is our body. Like the traditional virus these protein molecules then stimulate an adaptive immune response that teaches the body to destroy any pathogen, with the protein.

Will they be more potent than traditional vaccines?

Human being's immune system have two parts, first is the innate part, which is the defences we are born with and second is the acquired, which we develop as we come into contact with pathogens. Traditional vaccine molecules usually work only with the acquired immune system and the innate immune system is activated by another ingredient, called an adjuvant. Whereas, mRNA in vaccines could also trigger the innate immune system, providing an extra layer of defence without the need to add adjuvants.

Why does mRNA vaccine need to be stored at colder than Antarctica's winter?

This is the biggest challenge with mRNA vaccine, that it is inherently instable, and more likely to break apart above freezing temperatures. Since mRNA is fragile, and thus the vaccine has to be kept at very low temperatures to avoid degrading and thus giving little effective immunity to the recipient; for example, the BNT162b2 mRNA vaccine developed by BioNTech and Pfizer has to be kept at -70 degrees Celsius. (colder than the winter temperature in Antartica)

Another company Moderna, say that their MRNA-1273 vaccine can be stored at -20 degrees Celsius (comparable to a home freezer), and remains stable at 2 to 8 degrees Celsius.