DrEnmark sounded the alarm this week by announcing that it is culling the nation’s entire mink flock – the largest in the world – to stop the spread of SARS-CoV-2 in valuable fur species due to potentially dangerous mutations.
The leaps of viruses between species make scientists nervous – as do suggestions about potentially important mutations that result from those hops. In this case, the Danish authorities say they have found some genetic changes that may undermine the effectiveness of Covid-19 vaccines currently in development.
But is this latest development in the Covid-19 saga a cause for deep concern? Several experts consulted by STAT suggested that the answer to this question may not be.
“This hits all the scary buttons,” said Carl Bergstrom, an evolutionary biologist at the University of Washington. But Bergstrom and others have argued that while the virus’s tendency to infect mink bears, it is unlikely to lead to a nightmarish strain that is more effective in infecting people than the current human virus.
“I don’t think a strain adapted to mink poses a greater risk to humans,” said Francois Ballou, director of the Institute of Genetics at University College London.
We can never rule out anything, but in principle it should not. The transmission should definitely not be increased. I don’t see any good reason why the virus should be more severe.
Let’s take a look at what is known about the Danish situation, why inter-species jumps are making scientists anxious, whether mutations are likely to affect vaccine efficacy, and why Palux thinks this situation is “fantastically interesting.”
What happens in the country of Denmark?
Denmark is the world’s largest producer of mink. Around 28% of the supply produces this luxurious furs.
Unfortunately, mink is susceptible to SARS-CoV-2, a fact that emerged in April when the Netherlands reported an outbreak on mink farms there. Infected humans working on farms transmit the virus to captive minke animals, which are found in close quarters are ideal for the quick transmission from mink to mink.
From time to time, mink infects people – a phenomenon recorded in both the Netherlands and Denmark. The Danish Ministry of Environment and Food said in a statement that the country will kill its entire herd – which is estimated at 17 million animals – after discovering mutations in mink viruses that it believes will allow those viruses to evade the immune protection generated. With Covid-19 vaccines.
Why do they think mutated viruses will escape vaccines?
Experts outside the state are not clear on the basis of this claim. Marion Koopmans, head of virology at the Erasmus Medical Center in Rotterdam, the Netherlands, said that although there is some information released about the mutations that have been recorded, support for such a bold claim is not yet sufficient. Virus analyzes of the Dutch mink outbreak were performed.
“That’s a very big statement,” said Copmans. “One boom, I don’t expect it to have this dramatic effect.”
Emma Hodcroft, a molecular epidemiologist at the Institute for Social and Preventive Medicine in Bern, Switzerland, said outside experts did not have the genetic sequence data to look at. But Denmark uploaded 500 gene sequences to databases open to scientists around the world on Thursday, and is expected to add hundreds more in the coming days.
Experts will search these sequences for what the Danes saw and try to determine the effect that these mutations might have if the viruses they contained infect humans.
For now, however, Hodcroft agrees with Copmans. “It almost never happens to be a simple story of one mutation and all of your vaccines stop working.”
Frankly, she is more interested in how she handles the advertisement than she is about the results themselves. “It puts scholars and the public in a really difficult position when we have such statements that we have very little information or context,” Hodcroft said. “These things are not primarily black and white.”
How many species do they jump anyway?
Species jumping always makes scientists nervous. One of those events, after all, is how we ended up with the Covid-19 pandemic.
Viruses that usually infect one type of animal – let’s use bats as an example – that find their way to other species can cause severe disease in new species if the virus is able to transmit efficiently. Viruses can become entrenched – endemic – in new species.
For example, the four coronaviruses – SARS-2 cousins - that cause the common cold are thought to have spread from other species to humans at some point in the past. Events spread of the influenza virus – from poultry or pigs – occur from time to time. The H1N1 pandemic emerged in 2009 when the influenza virus that was circulating in pigs began to infect people.
Bergstrom said that after years of dealing with viral fallout such as the Ebola outbreak and influenza pandemic, in addition to early bounces of the Coronavirus like the SARS outbreak in 2003, people are prepared to worry about these events.
But he said that was a different situation. It is not a hopping virus unknown to humans of an animal type. In this case, the virus that has already adapted to spread between people jumped into the mink and now it jumps again every now and then.
Bergstrom believes it is wise for the Danish government to execute the herd of mink. But he is not sure that the changes made in the mink are likely to make the virus worse for people.
We used to feel fear before a pandemic when something from a distant species came to a closer one. Our intuition is not quite a good fit for what happens in the middle of a pandemic when something from us moves to distant creatures and then returns, ”he said.
Palux and others suggested that the changes observed in mink viruses may be a sign of the virus adapting to infect mink animals – potentially making the viruses less effective in humans over time.
Capture indirect effects in real time
Palux links the danger the spread poses to humans as “really, really small.”
But he said it’s exceptional to be able to actually capture what is happening in real time when the fallout occurs, and map out the genetic changes from the start.
Usually when such events occur, humans only learn what happens as the virus adapts to spread between humans. For example, the early changes that made SARS-CoV-2 capable of passing from a still unknown animal species to humans were never noticed.
It’s totally exceptional, ”said Ballou. “We are always [too] Late.”