The Maryland Zoo in Baltimore is preparing to vaccinate otters, chimps, lions and more against COVID-19

The big cats at the Maryland Zoo in Baltimore will be among the first in line.

They’ll saunter over to the edge of their enclosure, likely lured by a piece of ground meat, and present one of their hips to a waiting zookeeper, who will inject them with a specially made COVID-19 vaccine.


When all is said and done, they might even receive a “jackpot” prize, like flank steak, said associate veterinarian Dr. John Flanders.

In the next few months, the zoo will begin administering two-dose vaccines to 30 of its animals, Flanders said — from North American river otters to Amur leopards. Not all will be as easily persuaded as the felines.


“We’ve really focused a lot of effort on just minimizing risk and transmission as best as possible,” Flanders said. “And now, this vaccine is hopefully going to be another tool for us to help us minimize risk for if these animals get exposed.”

The vaccines will be donated by a company called Zoetis, which is providing 11,000 free doses of its COVID-19 vaccine to mammals living in 70 zoos and animal care facilities.

The company’s vaccine doesn’t use mRNA, like the Pfizer BioNTech and Moderna shots, or a viral vector, like the Johnson & Johnson vaccine. Instead, it uses synthetic spike protein made from that of SARS-CoV-2.

The zoo doesn’t have any vaccines in hand yet, but a shipment is expected in a few weeks to a month, said Jane Ballentine, a spokesperson for the zoo.

First will come the lions, leopards, bobcats and cheetahs, and the zoo’s American badger — high-risk animals who have been trained to receive injections in a cooperative manner. Vulnerable but less amenable species, including the zoo’s great apes and chimpanzees, will be in the second tier for vaccination. Some of those animals may need to be anesthetized to receive their shots.

“We anticipate they’re not all going to comply, or they might have a bad day that day,” Flanders said. “It just depends on their mood.”

Afterward, those primates might receive a particularly desirable piece of fruit, Flanders said.

The third and final tier will include lower-risk animals, such as lemurs. No COVID-19 cases have been discovered in that species, but experts worry that their membership in the primate family may make them susceptible to the virus.


The main is worry is that human keepers could transmit COVID-19 to animals unwittingly. At the Maryland Zoo, keepers and other staff have been donning masks and face shields to care for the animals since the pandemic began, Flanders said. Although zoo animals are unlikely to be exposed to the virus via patrons, they come in fairly close contact with any number of veterinarians, maintenance workers and keepers throughout their lives, Flanders said, all of who could expose them to COVID-19.

Some animals at the Maryland Zoo have been tested for COVID-19, Flanders said, but all have come back negative.

Another worry is that the virus, once inside an animal, could mutate, creating new variants for humans to contend with, said Xiaoping Zhu, chair of the University of Maryland’s Department of Veterinary Medicine.

Long-term, Zhu said officials should consider recommending COVID-19 vaccinations for more animals.

In the meantime, the world’s focus is still trained on vaccinating as many people as possible. Globally, roughly one-third of people are fully vaccinated, according to Our World in Data. In the United States, 53.9% of people have been fully vaccinated, according to the Centers for Disease Control and Prevention.

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But efforts to immunize animals don’t detract from that all-important aim, Flanders said.


“It’s not a human product. We’re not taking any human doses out of the circulation,” he said. “And it’s manufactured by a veterinary company. So it’s not that they are taking manufacturing away from human vaccine doses. This is completely separate.”

So far, the U.S. Department of Agriculture has confirmed 231 cases of COVID-19 in animals not on farms. There have been a series of damaging outbreaks on mink farms. In June, Oregon’s Department of Agriculture required mink ranchers to vaccinate their animals against the virus.

The most cases have been reported are among domestic dogs and cats, followed by tigers, otters, gorillas, lions, snow leopards and cougars.

The World Small Animal Veterinary Association has yet to recommend household animals receive the vaccine, particularly because the CDC has said the risk of animals spreading the disease to humans is low. The USDA is approving animal COVID-19 vaccinations only on a case-by-case basis. The Maryland Zoo is also keeping state veterinarians apprised, Flanders said.

Many animals have fared well after their diagnoses, although, notably, two lions died of COVID-19 at a zoo in India earlier this summer amid that country’s spike in cases tied to the delta variant. And Danish officials ordered millions of minks slaughtered after outbreaks at hundreds of farms there.

“Minks have been shown to be very susceptible to this, and it kind of runs rampant throughout their populations,” Flanders said. “I certainly do not want to even begin to think about that happening to one of our animal populations here.”