SALEM — Oregon’s campaign to vaccinate the public against COVID-19 is extending to the animal kingdom.
The state Department of Agriculture has filed an emergency temporary rule requiring coronavirus vaccines for as many as 212,700 farmed mink to reduce the risk of new infections, virus mutations and possible animal-to-human transmission, the agency announced May 28.
Mink farmers have until Aug. 31 to vaccinate their current animals. Any mink born or imported after that date must be vaccinated within 120 days of birth, or within 60 days of being brought into Oregon.
Farms must also agree to participate in additional surveillance testing per ODA and USDA guidelines.
“ODA is taking the necessary precautions to reduce the risk of infection in captive mink, as well as reduce the risk of potential mutation of the virus and the potential for virus transmission back to humans,” said Ryan Scholz, the state veterinarian. “It is critical that owner-operators vaccinate their mink against the virus.”
Surveillance testing will provide assurance the vaccine is effective, and infections are not occurring on farms, Scholz added.
The rule comes after one mink farm in Oregon was placed under quarantine for more than two months between late November and early February after multiple animals tested positive for the virus. Scholz said the mink had likely contracted the virus from workers at the farm.
ODA did not identify the farm for security reasons. The positive tests prompted concern about the possibility of a “viral reservoir” among captive mink spilling into the wild and infecting related species like river otters, fishers and martens.
After two consecutive rounds of follow-up testing at the farm revealed no new cases, the quarantine was lifted on Feb. 11.
The approved vaccine for minks was developed by Zoetis, the world’s largest producer of medicine and vaccinations for pets and livestock. The company, based in New Jersey, worked with Fur Commission USA, which represents mink farmers, on clinical testing for the vaccine last year.
Michael Whelan, executive director of the commission, said mink farmers were already working toward vaccinating their animals even before the Oregon rule was announced.
“We see the importance of keeping the mink healthy, keeping the workers healthy and keeping the public healthy,” Whelan said.
Farmers will bear the expense of vaccinating their own animals, Whelan said. Like the Pfizer and Moderna vaccine for humans, the Zoetis vaccine for minks requires two rounds of shots. The cost works out to about 77 cents per mink.
ODA spokeswoman Andrea Cantu-Schomus said Oregon has a maximum permitted capacity of 212,700 animals at registered mink farms, though the actual count is likely lower.
Fur Commission USA is assisting in the distribution of vaccines to veterinarians. The first phase of vaccinations in Oregon will likely begin this week, Whelan said.
In addition, Whelan said the USDA and Centers for Disease Control and Prevention are in the process of developing national protocols that will likely require vaccinating all mink nationwide. As of 2018, the U.S. had 245 mink farms in 22 states that produced 3.1 million pelts, according to the commission.
“Oregon was quicker to make an emergency rule because of the outbreak, but all mink in the country will be vaccinated before the end of July,” Whelan said.
As of December 2020, eight countries have reported cases of SARS-CoV-2 in farmed mink, including the U.S. Perhaps the most serious outbreak was in Denmark, where authorities ordered the entire farmed mink population of up to 17 million animals slaughtered.
Denmark also banned mink farming and breeding until at least 2022 after discovering a new strain of the virus that can be passed to humans, called the Cluster 5 strain.
While the Centers for Disease Control and Prevention states there is no evidence that mink play a significant role in spreading the coronavirus to humans, cases have been reported previously in the Netherlands, Denmark, and Poland.
Mink from a farm in Michigan and a small number of people were also infected with a mutated strain of the coronavirus, suggesting animal-to-human spread could possibly have happened in the U.S. Public health officials, however, say they would need more information to conclusively make that determination.
Those animals have since tested negative for SARS-CoV-2 twice, and the infected people have since recovered, the CDC reports.
Earlier this year, Oregon Sen. Floyd Prozanski, a Democrat representing parts of Douglas and Lane counties, sponsored a bill that would ban mink farms in Oregon. A hearing for Senate Bill 832 was held in April, but it failed to pass out of committee.