COVID-19: Have US public health authorities tried to suppress human-to-human transmission of the virus?

US government documents received National Geography provide the first behind-the-scenes look at the U.S. Centers for Disease Control and Prevention (CDC) investigation into a suspected case of animal-to-human spread of COVID-19 in Michigan in late 2020. The documents and statements made by the agency after their disclosure indicate that the CDC already knew that farm-raised mink potentially infected humans at least three months before they quietly released an update to their website in March 2021 of the year.

The delay in disclosing this alleged spread to the public may have hampered their ability to effectively track the spread of the SARS-CoV-2 virus, which experts say could affect another species, mutate and then return to humans, according to coronavirus researchers. as a more dangerous or more contagious variant.

“This situation should once again remind us that transparency is important and that the sooner we know, the sooner we can act,” said Scott Wiese, director of the Center for Public Health and Zoonoses at the University of Guelph in Canada. If information about suspected cases of spread had been released earlier, he said, it could help other countries better monitor and respond to the pandemic.

These thousands of pages of FOIA documents, many of which have been censored, contain emails exchanged between the CDC and Michigan health authorities formally requesting help from the organization as of October 8, 2020, following confirmation that that a mink from a local farm was contaminated. The emails show that in just a few days, the CDC sent four veterinary epidemiologists to Michigan to take samples from minks on the farm, as well as some people living nearby, to study the spread of the virus.

Ultimately, genome analysis of virus samples from two farm workers and two people with no known relationship to minks showed that they were infected with a unique variant of the coronavirus previously identified in these animals, and in cases of transmission from minks to humans identified in Europe.

The CDC defended its decision not to make a formal public announcement of the findings, which received minimal US media coverage other than a journal article. Detroit Free Press in April 2021, one month after the CDC updated its website. This was announced by one of their representatives, Nick Spinelli. National Geography emailed that all “relevant information” had finally been posted on the CDC website and that similar cases had been identified in Europe, the news was not “surprising or unexpected”.

Spinelli added that the genomes of these four virus samples were known to the public because they were uploaded to GISAID, a global public database specializing in viruses such as COVID-19, between November 4, 2020 and November 4, 2020. February 23, 2021. The database, however, requires users to register an account, know how to use the site, and be familiar with genomic sequence mapping.

Throughout the CDC investigation, their representatives have repeatedly said National Geography that there was “no evidence of mink spread to humans in the United States”, including in an email sent in early January 2021. However, internal e-mail correspondence and Spinelli’s statements show that these claims were false: As early as November 4, 2020, mink-related mutations were found in the viral genomes of two Michigan breeders, and by the end of December, the genome of a third case had also been sequenced and uploaded to GISAID.


There is no evidence that minks play a significant role in human spread of the virus or that mink-related variants have long circulated in Michigan communities, Spinelli said. In addition, residents of the state at the time did not need to take extra precautions, according to Angela Rasmussen, a virologist at the University of Saskatchewan in Canada, because health advice such as wearing masks and social distancing would not have mattered. changed.

According to the Centers for Disease Control and Prevention, these four Michigan cases are the only suspected mink-human side effects in the United States. Aside from minks, the only other animals that transmit the virus to humans are the white-tailed deer in Canada and the hamster in Hong Kong.

A growing number of other species, including lions, tigers, gorillas, hyenas, dogs and cats, appear vulnerable to COVID-19 but are unlikely to play a significant role in spreading the virus to humans. CDC and other experts.


According to Spinelli, the CDC can’t say with certainty that minks transmit the virus to humans. “Because we don’t have many genetic sequences from the communities living near the farm, we can’t know for sure if the mutations came from the mink on the farm or if they were already circulating in the community,” he says.

However, other experts say that although the mutations occur randomly, it is unlikely that the variant has a different origin. “The more mutations, the less likely they are to happen by chance,” Wiz says.

The lack of definitive answers in such studies highlights the need for more investment in sequencing the virus genome, both in humans and infected animals, Rasmussen said. Thus, epidemiologists could better fill in the gaps in their maps and understand how the virus is transmitted from one person or animal to another.

We don’t know much about the four Michigan residents, but the fact that two of them (who live in the same house, according to the Centers for Disease Control and Prevention) contracted the mink variant when they had no connection to the farm suggests that the variant spread. outside of it. farms, into the community, and continued to circulate for several months.

Four people made a full recovery, and a surviving mink from the affected farm later tested negative for the virus, Spinelli said.

The emails also show that Illinois was initially reluctant to allow Michigan mink skins to be farmed on its territory, but eventually accepted more than 17,000 in November 2021. mink farmers who have witnessed widespread outbreaks of coronavirus in their animals and are receiving increasing calls to put an end to the mink fur industry.

In February 2022, the US House of Representatives passed a law banning mink farming nationwide. The legislation has yet to pass the Senate, but it has received strong support from animal welfare organizations that accuse the industry of being inhumane and too risky for humans.

In March Ireland passed a law banning the breeding of fur-bearing animals. In 2020, Denmark and the Netherlands, the two largest mink producers, culled millions of farmed minks due to fears of the spread of COVID-19. The Netherlands voted to end mink farming immediately, thus hastening the already planned end of the mink fur industry.


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