In a press conference on Wednesday, Denmark's Prime Minister Mette Frederiksen announced that the country plans to cull up to 17 million minks. This decision, Danish Health Authorities say, is a preventative measure to avoid jeopardizing the development of a COVID-19 vaccine, after reports that a mutation of SARS-CoV-2 identified in the animal has spread to humans.
This announcement follows the eradication of hundreds of thousands of minks in the Netherlands, Denmark and Spain earlier this year amidst fears of mink-human transmission of SARS-CoV-2. "In the Netherlands, the genotype seen in mink was reported to have spread back to people, mostly workers, in the area around the farms. This led to the Netherland's decision to slaughter on a widespread basis," said Professor James Wood, head of the department of veterinary medicine at the University of Cambridge.
Data seems to be a key issue here. Despite the arguably bold decision to cull the Danish mink population, the country have not yet made the genomic analysis available to the public, or other Health Authorities. The World Health Organization shared the following Tweet earlier today:
A review published in September in Nature highlights minks as being "naturally susceptible to infection with SARS-CoV-2" and as such, a "suitable model" for use in laboratory studies of SARS-CoV-2, along with ferrets.1 The scientific community is calling for the data to be made available by Denmark as soon as possible so that it can be subjected to further analyses and the situation can be evaluated. Kasper Lage, associate professor at Harvard Medical School, said in a Tweet, "I really think the data needs to be released so researchers both Danish and international can help analyze and interpret them ASAP. This is clearly an issue that goes beyond Denmark."
Without the data, it is easy for speculation and fear to spread regarding mink-human transmission and the possible implications. Professor Francois Balloux from the UCL Genetics Institute has aired caution in making assumptions from the culling announcement. Writing in a Twitter thread he said, "#SARSCoV2 mutations acquired in minks are not concerning. We already knew that #SARSCoV2 can transmit from minks to humans. Though, this should be of no concern in terms of the evolution of the transmissibility of the virus." There are several scientific groups and consortiums across the globe, such as The COVID-19 Genomics UK (COG-UK) Consortium and The GISAID Initiative, to name two examples, that are exploring the genetic diversity of SARS-CoV-2 and monitoring its evolution.
Balloux added: "There are thousands of mutations in SARS-CoV-2 that arise constantly. The fact that a few have been observed in minks will not change the strains in circulation in humans. If they were beneficial for the virus to infect its human host, they would be at high frequency already."
As the scientific community awaits the release of Denmark's genetic data, the decision has been branded as a "precautionary stance" by Professor Ian Jones from the University of Reading, who said: "[Of course] the mink version may not transmit well to man so it’s a theoretical risk but Denmark is clearly taking a precautionary stance in aiming to eradicate the mink version so that this possibility is avoided or made much less likely.”
Reference: Muñoz-Fontela C, Dowling WE, Funnell SGP, et al. Animal models for COVID-19. Nature. 2020;586(7830):509-515. doi:10.1038/s41586-020-2787-6.