Countries across the globe have started coronavirus vaccination programme in a fight against the COVID-19 disease caused by SARS-CoV-2. On December 11, 2020, the U.S. Food and Drug Administration issued the first emergency use authorisation to Pfizer-BioNTech's COVID-19 vaccine for its use in the U.S. among individuals who are 16 years of age and older. Soon Pfizer-BioNTech's COVID-19 was rolled out in the United Kingdom (U.K.), Canada and several mainland European countries. India too initiated its coronavirus vaccination drive on January 16 with restricted emergency use provided to Covishield and Covaxin. Though all vaccines aim at providing immunity from the Novel Coronavirus, they are developed differently. For example, Pfizer-BioNTech's BNT162b2 and Moderna's mRNA-1273 use the genetic approach and have developed mRNA (messenger-RNA) vaccines. But what is an mRNA vaccine? NDTV spoke to experts to find out.