Up until recently, almost all of the focus on preventing the spread of the coronavirus has been on humans, but now scientists are looking at preventing the virus in other species.
This month, zoos across the country — including the Denver Zoo — will begin vaccinating some of their animals against COVID-19. Last year, several zoos reported positive cases in animals, including seven tigers and lions at the Bronx Zoo.
Cases of transmission between humans and animals are rare, but can happen. The CDC says the initial exposure event for the pandemic came from an animal, most likely a bat. But there’s still a lot about the coronavirus that’s unknown, especially in animals.
Mammals appear to be most susceptible, especially primates and big cats, said Dr. Scott Larsen, the Denver Zoo’s vice president of animal health and head veterinarian. The zoo has had no animal cases of COVID-19, Larsen said, adding that the vaccinations are really more a matter of taking every precaution available and being good stewards of the animals.
“It's important in terms of our stewardship and care of these animals to do what we can to protect them and provide the best possible care for them,” he said.
Developed by the veterinary vaccine company, Zoetis, the vaccine is fairly similar to its human counterpoint. The two-shot dose has a similarly high effectiveness rate. It was developed with both wild and domestic animals in mind, meaning that at some point, it will be available for pets.
Larsen says a very small percentage of domestic cats — and an even smaller percentage of dogs — have contracted COVID-19 since the pandemic began. That number is especially telling considering how much day-to-day, close contact people have had with their pets during periods of lock-down and isolation during the past year and a half, he said.
But it isn’t likely to be something that becomes mandatory, Larsen says.
“I don't anticipate it's going to be like a rabies vaccination, which is a big public health issue and why that is required in many parts of the country in terms of getting your dog in particular licensed,” he said. “It will be an option, and people will need to make up their own minds on whether they feel like there's enough of a risk there that they do want to get that vaccine or not.”
At the Denver Zoo, the “first wave” of vaccines will be given to primates and big cats. These are the animals that have shown not only the highest likelihood of contracting the virus, but also for getting really sick from it, Larsen said.
Not every animal at the zoo will be getting a vaccine, such as the zoo’s hundreds of fruit bats, he said. Their contact with humans is minimal and vaccinating such a large number at once would be incredibly challenging.
Visitors to the zoo shouldn’t be concerned about contracting the virus — at least not from the animals, Larsen added.
“This is really about protecting (the animals) versus mitigating a public health risk — that it's going to get into our animals and then pose a risk to our keepers, to the public,” he said. “That's not true of every single disease we may have to think about or deal with, but certainly with COVID. There's just magnitudes more cases in people than have been identified in animals, whether they're pets or wildlife.”
