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The "mink mutant virus" stories have focused too much on the mutations and not enough on the fact that we have a raging COVID-19 epidemic in mink. The decision by Danish authorities to cull its mink population is the right one, but not necessarily for the reasons given. Thread
The specific mutations - 69del, Y453F, I692V, M1229I (aka "Cluster 5") - may or may not be functionally important and may or may not have occurred in mink (except for Y453F, which appears to be a mink-specific ACE2 adaptation). Great thread 
2/ https://twitter.com/firefoxx66/status/1324095151984312324?s=20
2/ https://twitter.com/firefoxx66/status/1324095151984312324?s=20
While it's important to understand if such mutations could change e.g., SARS-CoV-2s antibody neutralization sensitivity, this is not a question specific to SARS-CoV-2 'mink' mutations - it's a much broader question about the virus' potential ability to evade humoral immunity.
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We don't know the answer to that Q, and we don't know how that relates to the effectiveness of future vaccines. While it’s not impossible that a single mutation could interfere with vaccine effectiveness, it’s unlikely - but what multiple mutations might do, we don't know.
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One word of warning on the latter point - it has often been speculated that because of the relatively low evolutionary rate of SARS-CoV-2 (compared to e.g., flu), vaccine escape should not be a concern.
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While that may potentially be true, we cannot conclude that without direct data. Furthermore, these statements focus on the substitution rate and fail to consider SARS-CoV-2s recombination rate, which is high (but extremely low/zero for flu - although it can reassort).
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So why do we have to eliminate (or greatly minimize) the COVID-19 epidemic in mink? Because letting the virus run freely through yet another mammalian host could set us up on unexpected evolutionary pathways. Two primary concerns
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1. Broadening of SARS-CoV-2s host rage due to adaptation. Right now, humans serve as the (almost) exclusive reservoir for new infections. We cannot afford SARS-Cov-2 establish itself in other species such as mink, where it could potentially also jump to other animals.
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2. Mink are farmed animals and typically stacked in cages, creating different selection pressures than those seen in the human population. E.g., could we see selection for increased transmissibility or longer infectious periods in mink? Possibly, and there are many unknowns.
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To summarize, for SARS-CoV-2 in mink, we cannot afford a parallel epidemic, as it will further fuel the COVID-19 pandemic and could set us up on unexpected evolutionary pathways. So the decision by Danish authorities is correct, but not (necessarily*) for the reasons given.
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*Why include "not necessarily"? Because the data for Cluster 5 is N/A. If a lineage of SARS-CoV-2 that is (a) a result of mink evolution, and (b) significantly resistant to neutralization by polyclonal Abs, that would require severe mitigation due to specific mutations.
11/fin?
11/fin?
