Intended for healthcare professionals

Letters Covid-19: new variants

Covid-19 and evolutionary pressure: can we predict which genetic dangers lurk beyond the horizon?

BMJ 2021; 372 doi: (Published 26 February 2021) Cite this as: BMJ 2021;372:n445
  1. Stephen T Green, honorary professor of international health and consultant physician1,
  2. Lorenzo Cladi, associate head of school (teaching and learning)2
  1. 1Sheffield Hallam University and Sheffield Teaching Hospitals, Royal Hallamshire Hospital, Sheffield S10 2JF, UK
  2. 2School of Law, Criminology, and Government, University of Plymouth, Plymouth PL4 8AA, UK
  1. steve.green5{at}

Emerging data show that the B.1.1.7 variant of SARS-CoV-2 might be associated with an increased risk of death.1

As Charles Darwin taught us, the evolution of living creatures is inevitable. The evolutionary process can progress down many different pathways, and—regardless of whether philosophers and biologists consider viruses to be “living creatures”2—natural selection applies as much to SARS-CoV-2 as it does to any living entity, including human beings.

Given the view that SARS-CoV-2 might have come into existence through the chance encounter of a bat and a pangolin,3 and in light of the recent independent emergence of at least three new (and potentially very dangerous) variants around the world,4 scientific imaginations need to be exercised like never before to anticipate the next steps in this unfolding human tragedy.

Could human SARS-CoV-2 re-enter other animal species and—as seems to have happened with the bat and the pangolin—encounter and combine with other animal coronaviruses to create yet more variants, some of which might prove to be dangerous to humans? This is not an outlandish idea—events of this type happen all the time with influenza5 and have considerable proved potential to damage human health. There have already been suspicions about SARS-CoV-2 variants from mink.6

SARS-CoV-2 is a clear and present danger. All things are possible, and no possibilities can be discounted without sufficient evidence. Engaging in the process of blue sky thinking is a long and tough road,7 but it has to be followed if the human race wants to get ahead of the covid-19 curve, and for maximum chances of success, the effort undoubtedly has to be international and inclusively worldwide.8


  • Competing interests: None declared.

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