Intended for healthcare professionals


mRNA vaccines: hope beneath the hype

BMJ 2021; 375 doi: (Published 24 November 2021) Cite this as: BMJ 2021;375:n2744
  1. Andy Extance, freelance science journalist
  1. Exeter, UK
  1. aextance{at}

mRNA vaccines have proven themselves as the most effective covid-19 vaccines, and their makers are now seeking to help conditions from cancer to HIV. Andy Extance investigates their promise and limitations

The next decade will “see a revolution in mRNA therapeutics,” says Paul Burton, chief medical officer at Moderna in the United States. Along with Germany based BioNTech, Moderna has already shown, by changing the course of the covid-19 pandemic, how powerful medicines based on messenger ribonucleic acid (mRNA) can be (box 1). The companies had originally planned to use their technology for other conditions, particularly cancer. After more than 10 years spent developing the technology, they’re now set to use their covid-19 success as a springboard to achieve their original goals.

Box 1

How mRNA covid-19 vaccines work

Until 2020, most vaccines used either disabled forms of bacteria or viruses or protein molecules that form part of the shell that wraps around the genetic material at their centre.

Covid-19 vaccines from Moderna and BioNTech instead deliver a genetic molecule called messenger RNA (mRNA) directly to cells. These encode an antigen—namely the spike protein from the outer coating of SARS-CoV-2 that lets the virus grab onto our cells. The human cell’s own machinery then makes the antigen from the mRNA template and the resulting protein provokes an adaptive immune response. Thus, the body learns to identify, target, and destroy that protein, including live virus particles.

As Moderna’s Paul Burton puts it, they “use your body’s cellular machinery to translate that messenger RNA into a protein that is perfectly designed for human beings.” Dealing directly with the genetic sequence makes vaccines much faster to develop than traditional methods.


Moderna has several therapeutic targets in its sights: from heart failure1 and faster, more effective influenza shots2 to the mosquito-borne viral disease chikungunya.3 BioNTech, meanwhile, hopes to …

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