9 November 2020
Mink – Denmark mutation
Added 9 November 2020 Concern has been raised regarding a mutation detected in mink in Denmark and evidence that this has already been passed on to humans. This has led to the decision to cull up to 17 million mink in Denmark and to travel bans being applied to people from Denmark. A statement from the Statens Serum Institute, Copenhagen, reported in English translation, stated that at that time, COVID-19 infection had been recorded in Denmark on 216 mink farms and that new mink variants of COVID-19 virus had been found in humans. So far, 5 different groups or clusters of mink variants have been found in Denmark through whole genome sequencing (WGS). Mink variants have been found in 214 people among 5102 samples that have been completely sequenced of which 200 (94%) where in people in the North Jutland region, accounting for 40% of the samples sequenced in that area. A specific virus from cluster 5, with 4 simultaneous changes in the genes for the spike protein, has been detected in 5 North Jutland mink farms and in 12 patient samples. Of these, 4 people were directly connected to 3 of these farms, suggesting onward transmission in the human population. Although initial observations suggest that the clinical presentation, severity and transmission rate are similar to other SARS-CoV-2 strains, the report also states that “Preliminary studies suggest that this virus from cluster 5 exhibits decreased susceptibility to antibodies from more individuals with past infection compared with non-mutated virus. This has been demonstrated in laboratory experiments, where it is seen that the particular mink virus is not inhibited to the same degree by antibodies from humans who have been infected with SARS-CoV-2 compared with other non-mutated SARS-CoV-2 viruses”. This has led to concerns that the immunity gained through vaccination or past infection may also be reduced, although at present this has not been proven, and studies are ongoing. As a result of these findings the World Health Organisation issued a risk assessment and advice including:- further virological studies should be conducted to understand the specific mutations described by Denmark and to further investigate any epidemiological changes in function of the virus in terms of its transmissibility and the severity of disease it causes.
- all countries to increase the sequencing of SARS-CoV-2 viruses where possible and sharing the sequence data internationally.
- countries to strengthen farming biosafety and biosecurity measures around known animal reservoirs to limit the risk of zoonotic events associated with SARS-CoV-2. This includes infection prevention and control measures for animal workers, farm visitors and those who may be involved in animal husbandry or culling.
- BBC News (2020) Denmark to cull up to 17 million mink amid coronavirus fears
- BBC News (2020) Coronavirus: UK bans Denmark visitors over mink Covid-19 fears
- WHO: Emergencies preparedness, response (2020) SARS-CoV-2 mink-associated variant strain – Denmark
- OIE (2020) Guidance on working with farmed animals of species susceptible to infection with SARS-CoV-2