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Covid-19: Denmark to kill 17 million minks over mutation that could undermine vaccine effort

BMJ 2020; 371 doi: (Published 09 November 2020) Cite this as: BMJ 2020;371:m4338

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SARS-CoV-2 and minks, how much should we worry?

Dear Editor,

As we are well aware, a number of domestic and wild animal species have been reported to be (more or less) susceptible, either naturally and/or experimentally, to SARS-CoV-2 infection, with additional work comparing the "homology degree" of the ACE-2 viral receptor among several terrestrial and aquatic mammal species having made available a remarkable set of interesting data about the "potential susceptibility level" of the aforementioned species to SARS-CoV-2.

In this respect, however, as I have also emphasized in an "e.Letter" published in Science (1), we should also pay attention, I believe, to the inter-species homology degree of "neuropilin-1", a recently identified "co-receptor" facilitating SARS-CoV-2 cell enry and infectivity (2).

To the best of my knowledge, when taking a look at all the species to which SARS-CoV-2 has been "successfully" transmitted, under both natural and experimental conditions, minks rank as the only animals which have (spontaneously) acquired the virus from humans (spillover) and which have (still naturally) "returned" it to man (spillback), thus far. Additionally, and even more important, a new SARS-CoV-2 variant, provisionally named "cluster 5" and different from the SARS-CoV-2 strains circulating across the human population, has been described in fur minks intensely reared in Denmark as well as in local mink farmers (with further variants, carrying up to 3 aminoacid substitutions and 1 aminoacid deletion within their "spike protein's subunit 1", having been also detected in mink farms from the Netherlands as well as from other European Countries).

These findings are of concern for a number of reasons, with special emphasis on the possibility that the new "cluster 5 variant" identified in minks (and passed by them to mink farmers, an absolutely unprecedented finding, thus far!) could be less "immunogenic" as compared to the SARS-CoV-2 strains commonly infecting, and circulating among, people, coupled with the additional possibility that the forthcoming anti-SARS-CoV-2 vaccines - which should start to become publicly available within the next few months, most hopefully (!) - could not confer an adequate level of immune protection against the aforementioned viral isolate detected in minks.

While much more, "ad hoc" and in-depth research is urgently needed in order to provide a set of solid data and reliable answers to the above issues, I still believe that, when trying to "see things" as if we were the virus - thereby following the outstanding "legacy" left to us by Theobald Smith with his memorable "quadrilater" - SARS-CoV-2 should not be so "interested", after all, in gaining (spontaneous) access into "new species", provided it has a pandemic potential of almost 8 billion people in front of itself! And, it is among our chief responsibilities to prevent this from happening (until when one or more safe and effective vaccines will be available for all, at least!) through our individual behaviours and "life styles" in correctly wearing face masks, in keeping "physical distance" (I definitely prefer to use the adjective "physical" rather than "social") from, and in non grouping with, others, as well as in frequently disinfecting and/or washing our hands.

1) Di Guardo G. (2020) - Virus-neuropilin-1 interaction and animal models of SARS-CoV-2 infection (e.Letter). Science (
2) Cantuti-Castelvetri L., et al. (2020) - Neuropilin-1 facilitates SARS-CoV-2 cell entry and infectivity. Science 370:856-860.

Competing interests: No competing interests

24 November 2020
Giovanni Di Guardo
Professor of General Pathology and Veterinary Pathophysiology
University of Teramo, Faculty of Veterinary Medicine, Località Piano d'Accio, 64100 - Teramo, Italy