Mink with coronavirus: what's the danger?
Since July, over 200 people in Denmark have been infected with copies of the coronavirus that have been spreading through mink farms. And crucially, the mink have given 12 of those people a unique version of the virus. Reportedly this version has been transmitted human-to-human as well, although it’s not clear whether this is still going on. To address the problem scientists are now trying to understand how the virus behaves in minks, and whether the unique version that comes from minks presents a unique problem for treatments. Alina Chan is a scientist from the Broad Institute of MIT and Harvard who wasn’t involved with the Danish research, but has been looking into COVID in minks, and explained the situation to Phil Sansom…
Alina - In Denmark they have more than 1100 mink farms. More than 200 have been found to have COVID-19 outbreaks. And now that virus that has been circulating among the minks has passed back into the human population in Denmark.
Phil - Wow. You know, I wouldn't have put minks as top on my list of COVID threats.
Alina - Yeah, this is not too surprising, although it's really devastating to hear this news. That's because we have known for a while - scientists have known for a while - that SARS-type viruses can infect ferrets, which are in the same family as minks. And so it's not surprising that minks are susceptible to SARS-2.
Phil - So is this the first time that minks have got SARS-CoV-2?
Alina - No, this is not the first time that this whole scenario of transmission from humans, to minks, to humans has been observed. As of today, there are at least six countries that have reported these mink outbreaks. So we've got Denmark; but the first was actually the Netherlands, and they were the first to report a mink outbreak back in April of this year.
Phil - Do we know what happens to the virus when it's in the minks?
Alina - This part is kind of a mystery, pr I'd say at least an ongoing study. There were two publications that just came out. One of them is by the Dutch group; there are a few caveats in their approach, but they said that they see some hints of faster evolution of the virus in the minks. More analysis needs to be done, and by independent groups of scientists. The other publication is by the Danish group, but this is a working paper, and so they have not shared their mink genomes yet; although they have committed to the WHO that they will.
Phil - So we don't have the full picture then of what the virus looks like in the minks. But am I right that we do know what the virus looks like once it's left minks and is back in humans again?
Alina - Yes, we can see what could be the mink associated variants coming out back into the human population in these two countries as well. In Denmark there's one cluster that is particularly concerning; it's called Cluster 5. A cluster is a group of SARS-2 sequences, in this case, that look really similar to each other. This cluster has a combination of different mutations in the spike gene; this is what helps it to infect different host species, and it's also the target of some of the most potent therapeutic antibodies.
Phil - What are the mutations?
Alina - They see about three to four different mutations. And actually each one of them has been around since at least March, across many countries and continents. So the individual mutations, they are not novel, but as a combo, they're novel. But they found that the most recent mutation, I692V... no other country in the world has detected it, and it only appeared in August.
Phil - I mean… what's the implication?
Alina - According to the Danish paper that came out, they got convalescent plasma from patients, and they found that in some of the cases, the plasma was not able to neutralise the new mink associated variants. And so now they are a bit worried that this could have an impact on antibody therapeutics, or vaccines in development. But again, just to emphasise the effect that they saw, it's not that drastic, but it does suggest that people who don't have long lasting immunity could be susceptible to this new variant.
Phil - So what's your take? Is the virus now more dangerous that has gone through minks?
Alina - I don't know. I think that's the answer that most scientists would tell you, is that we just don't know. I don't think people should panic. When I say mutations, it doesn't mean that every single mutation makes these viruses more transmissible, or more dangerous for humans. Not at all. In fact, many of them could actually be taking a step backwards, considering that they are adapting to a different animal species. What the worry here is besides from these mink farms being a pool, they are generating more diverse viruses. So if these different variants, even if some of them are weaker in humans, if they enter the human population again, and we start implementing a widespread vaccination, for example, this will select for those rare variants that vaccines don't work as well against.