The global race to produce coronavirus vaccines, in particular the development of messenger RNA or mRNA technology, has given hope to researchers who have struggled for years to produce shots that could save millions of lives.
Vaccines take several forms, with some made from bacterial or viral particles treated to prevent virulence, while others consist of inactivated or weaker virus particles.
Yet more are made from components of the pathogen or, like the Oxford-AstraZeneca Covid-19 vaccine, consist of viral vectors that deliver genetic material into the cells of recipients.
Two of the earliest-approved and most effective vaccines against coronavirus, from Pfizer-BioNTech and Moderna, are based on mRNA technology.