In Denmark, a new strain of SARS-CoV-2 has been identified that can be transmitted from minks to humans. How dangerous is this and why?
On November 4th, a news story spread that quickly gained the attention of all mainstream media. The Danish government announced that it would eliminate 17 million minks bred in captivity, as they are potential coronavirus “spreaders” for humans.
What makes minks different from cats and dogs? Why put them down?
Since the beginning of the pandemic, more than 50 species of animals have been found to be positive for the dominant strain of SARS-CoV-2; among these dogs, cats and monkeys. However, since no cases of transmission from these animals to humans have ever been detected, it was never necessary to intervene.
The situation with minks is different because, following strict controls that are performed, in order to control the spread of COVID-19, Danish scientists have identified a new strain of SARS-CoV-2 that has four mutations that differentiate it significantly from the known strains responsible for the infectious disease.
The main feature of this new strain is that it seems to allow the coronavirus to be transmitted from mink to human through a process called zoonosis. The same process that allowed SARS-CoV-2 to jump species over a year ago, infecting the first human in Wuhan, China.
What are the consequences of the mutation in minks?
The gene sequence of the new strain of SARS-CoV-2 was entered into a public database only a few days ago, and therefore studies are still ongoing by all interested research groups. However, the first analyses carried out by the Danish scientists and which generated the alarm, have highlighted at least four mutations of the spike protein that determined the ability of the coronavirus to be passed from mink to human.
At the moment only 12 people are infected and display non-serious symptoms. However, the most important consequence is the fact that the coronavirus transmitted from minks to humans doesn’t respond to neutralizing antibodies that act against the dominant strain of SARS-CoV-2. Therefore, the worrying thing is that our immune system can’t leverage the developed weapons (i.e. neutralizing antibodies) against the new strain.
What impact could this have on the development of a vaccine?
Even though you may have already been infected with COVID-19, you may still become infected with a new strain. The most important consequences are for the vaccine under development that could either be a little (or not at all) effective. This is because the vaccine aims to induce antibodies against the spike protein, so that the virus can’t be introduced into human cells.
So far, thousands of mutations have been identified in the gene sequence of SARS-CoV-2, and only in this case does there seem to be a real impact on its ability to infect human cells. The new mutations are in the coding region for the spike protein; however, vaccines contain many different parts of this protein that are used to push the immune system into producing antibodies against the virus.
The good news is that the mutations present in the coronavirus transmitted by minks are unlikely to render the vaccines completely ineffective. However, the question should be: how effective would they be?
What is the Danish government currently doing?
The Danish government, as soon as it became aware of this new strain and its potential danger, immediately took very tough security measures. More than 17 million minks in more than a thousand farms, have been culled with an economic impact of about USD $785 million. In addition, a lockdown was imposed on a rather large portion of Denmark, where about 280,000 people live.
These measures have been taken, despite the fact that there are only 12 cases of transmission from minks to humans. Alternatively, at least this is the number of people who have developed symptoms and therefore triggered the research that led to the identification of the new viral strain.
The fear of the Danish government lies in the fact that the 12 symptomatic individuals, as we’ve described previously, do not respond positively in forming antibodies, and this is a danger for the effectiveness of the vaccine (something remaining to be verified). In addition, it’s not yet known how long these people have been asymptomatic, and therefore with how many other people they’ve come into contact with before the diagnosis. For this reason, the Danish government has immediately circumscribed the area, in order to minimize the risk of the uncontrolled spread of the new strain of coronavirus.
But the minks (being farmed), where did they contract the virus?
Most likely, they’ve contracted it from one or more humans who have transmitted it to them. Then, the minks have played the role of “vessels” for the virus. This case brings to light the incidence of intensive farming on zoonoses. When animals live in captivity, viruses find a great breeding ground to test mutations that make them more infectious — and not always less lethal.
In general, we should reflect on how we manage animals of economic interest and animals for food consumption; we need to find a balance with nature that shields us from zoonoses and restores dignity to animal life.
The news has exploded in recent days, but the World Organisation for Animal Health (OIE) reports that six countries (Denmark, the Netherlands, Spain, Sweden, Italy and the US) have already reported the spread of SARS-CoV-2 infection in mink farms. Therefore, what’s been observed in Denmark may not be the only case.
This is a video from a Canadian News Outlet, demonstrating the intensive breeding in Denmark, and the quality of life of these animals.
This post is also available in: Italiano