DThe enmark rang alarm bells this week with the announcement that it was destroying the nation’s entire weasel colony – the largest in the world – to stop the spread of SARS-CoV-2 in the Furs are prized for potentially dangerous mutations.
The virus’s inter-species jumps worry scientists – as are the hints of possible mutations from those jumps. In this case, the Danish authorities said they had found some genetic changes that could reduce the effectiveness of the Covid-19 vaccine currently in development.
But is this latest turning point the reason why Covid-19 saga is so concerned? Several STAT experts consulted suggesting that the answer to that question is probably no.
“This hits all the scary buttons,”; said Carl Bergstrom, an evolutionary biologist at the University of Washington. But Bergstrom and others argue that while the weasel’s tendency to infect weasels is on track, it is unlikely to lead to a more effective strain of nightmares that infects humans than the virus. present in humans.
Francois Balloux, director of the Institute of Genetics at University College London, said: “I do not believe that a strain adapted to weasel will pose a higher risk to humans.
“We can never rule out anything, but in principle we cannot. It should definitely not increase transmission. I don’t see any good reason for the virus to worsen, ”he said.
Let’s take a look at what is known about the Danish situation, why inter-species jumps cause scientists to worry, whether mutations are likely to affect vaccine efficacy, and why Balloux thinks this situation is “extremely interesting”.
What’s happening in the state of Denmark?
Denmark is the world’s largest mink producer; it produces about 28% of the supply of this luxury fur.
Unfortunately, mink is susceptible to SARS-2 virus infection, a fact that came to light in April when the Netherlands reported an outbreak on mink farms there. Infected people working on farms pass the virus to captive mink, which are kept in close proximity ideal areas to quickly transfer from mink to mink.
Occasionally, weasels infect humans – a phenomenon noted in both the Netherlands and Denmark. In a statement, the Danish Ministry of Environment and Food said the country would destroy its entire herd – an estimated 17 million – after finding mutations in the mink virus it believes will allows those viruses to evade the immune defenses being produced. with Covid-19 vaccine.
Why do they think the mutant viruses will evade the vaccine?
Experts outside the country are not clear on what the claim is based on. “ Although there is some published information about the mutations that have been documented, it is not enough to support this, ” said Marion Koopmans, chief of virology at the Erasmus Medical Center in Rotterdam, the Netherlands. Such a bold statement. Virus analyzes from the Dutch mink outbreak were conducted.
“It’s a huge statement,” said Koopmans. “A single mutation, I wouldn’t expect that dramatic effect.”
Emma Hodcroft, a molecular epidemiologist at the Institute of Preventive and Social Medicine in Bern, Switzerland, says outside experts do not have genetic sequence data to consider. But Denmark uploaded 500 gene sequences into an open database for scientists globally on Thursday and is expected to add hundreds more in the coming days.
Experts will study those sequences looking for what the Danes saw and try to determine the impact of these mutations if the virus containing them infects humans.
However, for now, Hodcroft agrees with Koopmans. “It’s almost never been a simple story about a mutation and all of your vaccines stopped working.”
To be honest, she’s more interested in how the message is handled than about the findings themselves. “It puts scientists and the public in a really difficult position when we have statements like this that we have very little information or background on,” said Hodcroft. “These things basically never come in black and white.”
What’s the big problem with jump species?
The species’ jumps always worry scientists. After all, such an event is how we end up with the Covid-19 pandemic.
Viruses often infect one animal – let’s take a bat for example – finding a way into another species that could cause serious illness in the new species if the virus was able to transmit it effectively. Viruses may become entrenched – endemic – in new species.
For example, it is thought that four coronaviruses – cousins of SARS-2 – that cause the common cold have been spread from other species to humans at some point in the past. Flu virus transmission events – from poultry or pigs – happen over time. Pandemic 2009 H1N1 broke out when a flu virus circulating in pigs began to infect people.
Mr. Bergstrom said that after years of fighting the spread of viruses such as the Ebola epidemic, the pandemic flu plus the previous outbreak of coronavirus like the 2003 outbreak of SARS, people can worry about the events. this.
But here’s another situation, he said. It is not a virus unknown to humans that jumped from an animal. In this case, a virus that has adapted to human-to-human transmission has changed to weasels and now returns occasionally.
Bergstrom thinks that the destruction of weasels is a precaution by the Danish government. But he’s not sure the changes that happen in weasels are likely to make people worse.
“We are used to being scared before a pandemic when something from a distant species comes to a closer one. And our intuition isn’t quite right about what happens in the midst of a pandemic when something goes from us into a distant species and then back, ”he said.
Balloux and others suggest that the changes seen in the mink virus could be a sign of the virus adapted to infecting mink – which could make the virus less effective in humans over time.
Record your spread in real time
Balloux pegs the risk that diffusion poses to humans is “really, very small.”
But he says it’s special to be able to grasp in real time what will happen when diffusion happens and chart genetic changes in the first place.
Usually, when such events happen, people only realize what is going on when a virus has adapted to spread within the person. For example, the initial changes that make SARS-2 capable of transmitting from an unknown animal to a human have never been observed.
“It’s absolutely special,” said Balloux. “We always are [too] late. “