key: cord-0930881-tvm3d2hb
authors: Frutos, R.; Devaux, C. A.
title: Mass culling of minks to protect the COVID-19 vaccines: is it rational?
date: 2020-11-17
journal: New Microbes New Infect
DOI: 10.1016/j.nmni.2020.100816
sha: c3ff746c5fc80e99fd959a99ac998138f7dbe1cc
doc_id: 930881
cord_uid: tvm3d2hb

The Danish Government announced the culling of 17 million minks in rearing after the report of mink-specific mutations of severe acute respiratory syndrome coronavirus 2 in humans. The rationale behind this decision is that these mutations might negatively impact the deployment of anti-coronavirus disease 2019 vaccines. Is it a precautionary attitude or a panic-driven overreaction?

A rational attitude would be to isolate those minks while more information is gathered on the true meaning of the mutations observed. SARS-CoV-2, like other coronaviruses and RNA viruses, is evolving through a quasispecies mechanism [2] [3] [4] . A main characteristic of the quasispecies evolutionary process is the generation of post-infection mutations under positive selective pressure, i.e. host-driven viral evolution [5] . Therefore, mutations are not preexisting but instead acquired after infection and are specific to the host, usually allowing the virus to escape host defense mechanisms [6, 7] . SARS-CoV-2 can infect both humans and minks, each one being a source of infection [8] . SARS-CoV-2 variants reported in minks in Denmark [1] are very likely to be "mink signatures", i.e. adaptation to the host. In turn, humans infected with a virus coming from minks are most likely to force the virus to mutate to evade the human immune defense. Mutations in humans will thus be different than those in minks.

Mink is not the only species outside humans to be infected by SARS-CoV-2. Many other wild animals such as bats, pangolin, palm civet, ferret, monkeys, turtles, snakes and even whales can potentially be infected since they bear a compatible ACE2 receptor [9] . However, this is not limited to wild animals and several domestic species display the same trait, i.e. cats, dogs, pigs, sheep, cows, water buffalos, goats or pigeons [9] . These wild and domestic animals present the same risk of infecting humans back with SARS-CoV-2. COVID-19 has been clearly shown in cats and dogs who are humans closest companions [10]. Should we take the same decision as with minks and cull them? This would be an irrational behavior. Minks might show specific mutations because of the mass rearing conditions and containment which generate a high populations density, a high rate of contacts and fast frequency increase of viral genotypes having evolved in the host. The spillover model of preexisting adapted "human-active" genotypes in the wild has never been demonstrated and another model, the circulation model, has been proposed to explain the in-host evolution of 'human-active" mutations after transmission and circulation of the virus in humans [9] .

Fear is commonly observed in face of a pandemic. However, fear and panic should not be the drivers as they lead to irrational reactions. Culling millions of animals with no evidence of actual danger but simply on fear, is setting up a dangerous precedent. The risk is high then to consider that the safest way of protecting humans from any zoonosis would be to eradicate animals around. Humans are exposed to diseases. It is a natural process we cannot deny and we cannot avoid. The right attitude is not to cull and eradicate all putative threats for precaution but instead, since we occupy all the planet with a very large and still growing population, to ask ourselves how human activities impact the emergence and diffusion of infectious diseases. Human activities are the real drivers of epidemics and pandemics. The rational behavior would then be to organize these activities properly to reduce that risk instead of building a safety dome by eradicating all supposed sources of infection.

WHO 2020

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