If the new SARS-CoV-2 variants recently identified in mink spread widely in the population it could potentially affect the level of overall effectiveness of vaccines under development, warns the European Centre for Disease Prevention and Control (ECDC) in a new Rapid Risk Assessment published today (12 November 2020).
On 5 November 2020, Denmark reported 214 COVID-19 cases infected with SARS-CoV-2 virus variants related to mink as well as infected mink on a number of mink farms. These variants have also been found in people living in the affected areas. Twelve human cases were infected with strains showing four genetic changes in the S protein, three substitutions and one deletion. The 12 human cases were reported in August and September 2020. Not all cases had a direct link with a mink farm.
When the virus is introduced into a mink farm, it spreads quickly; principally due to the large number of infections and possibly due to biological differences between minks and humans, the virus can accumulate mutations more quickly in minks and spread back into the human population, the ECDC says.
There is currently high uncertainty regarding the nature of these mutations and their implications for vaccine effectiveness. ECDC is therefore closely monitoring the developments in Denmark.