Loretta is among 77 chimpanzees at a sanctuary in Georgia that may soon self-administer an experimental vaccine designed to protect them from COVID-19.

As the COVID-19 vaccine rollout has continued in the United States, a parallel vaccination effort has taken place in some U.S. zoos to protect their animals, particularly great apes. Now, a chimpanzee sanctuary in Georgia is ready to do the same, saying it intends to soon give an experimental COVID-19 vaccine to its primates, who are likely also vulnerable to the pandemic coronavirus.

“Having consulted with our vet and several other zoo individuals, we’re confident that it’s the right decision for us,” says Ali Crumpacker, executive director of the Project Chimps sanctuary. Additional U.S. chimp sanctuaries tell Science they are discussing whether to vaccinate their animals and will watch others’ efforts closely. But some say they don’t see a pressing need to do so, given other precautions they have taken.

Primatologists have worried about great apes, both captive and in the wild, since the start of the pandemic. Chimpanzees, gorillas, orangutans, and bonobos all share versions of the angiotensin-converting enzyme 2, the cell surface receptor to which SARS-CoV-2 binds to initiate infections. Moreover, human respiratory infections have devastated great ape populations in the past. “Great apes are susceptible,” to COVID-19, says Jon Epstein, vice president for science and research at EcoHealth Alliance, a nonprofit devoted to protecting wild animals, and people, from pathogens. “There are real, legitimate conservation concerns with this infectious disease.”

In response, zoos, sanctuaries, and national parks around the world tightened measures to protect their great apes against COVID-19, increasing their use of masks, gloves, and other personal protective equipment (PPE) and further restricting access to the animals. Still, concern grew in January 2021 when eight gorillas at the San Diego Zoo Safari Park contracted the virus. They survived, with just a fit of coughs and congestion to show for it, but the experience led the facility to become the first zoo to vaccinate, giving jabs to nine orangutans and bonobos in February. The animals received an experimental nonhuman COVID-19 vaccine provided by Zoetis, a U.S. company that was originally the animal division of Pfizer. The shots, like one for people made by Novavax that proved 90% effective against symptomatic infection in clinical trials, uses engineered spike proteins from SARS-CoV-2 to elicit an immune response against the virus .

COVID-19 is here to stay for a long time, and our animals are part of our community,” says Nadine Lamberski, chief conservation and wildlife health officer for the San Diego Zoo Wildlife Alliance. “To get herd immunity in our community, we need to vaccinate as many individuals as possible.”

Behind the scenes, other zoos and sanctuaries were paying attention. San Diego reported earlier this year that its primates had developed no serious adverse effects to the vaccine, just a few mild reactions such as signs of a headache. Soon after, Zoetis announced that more than 70 zoos, sanctuaries, and other institutions across the United States had requested doses. More than a dozen zoos have started to vaccinate otters, great apes, bears, and other animals.

Now Project Chimps, founded in 2014 and one of six accredited U.S. chimp sanctuaries that house great apes from research labs, the pet trade, and the entertainment industry, is about to receive a shipment of the Zoetis vaccine for its 77 chimps. Although the sanctuary already has COVID-19 precautions and more than 95% of staff are vaccinated, they wanted the extra protection for their animals. “We felt reassured by the fact that [zoos] went first and have seen no downsides,” Crumpacker says.

The U.S. government declared in 2015 that it would stop funding invasive chimpanzee research, and in 2016 the largest private chimpanzee research facility in the world pledged to send all 220 of its chimpanzees to Project Chimps within 5 years. That process has been slower than expected and mired in controversy; so far, 80 chimps have been relocated to Project Chimps.

About 70% of the chimpanzees at Project Chimps have been trained to receive voluntary injections, and the staff is working on preparing the rest. Crumpacker says they will not force the vaccine on chimpanzees that refuse shots and will instead try to vaccinate them later.

But leaders of Chimp Haven, the largest and only federally funded chimpanzee sanctuary in the United States, have decided not to order the vaccine for now. They believe the risk of their chimpanzees contracting COVID-19 is low, given the use of PPE and a high vaccination rate in caretakers. To date, there have been no recorded cases of chimpanzees testing positive for COVID-19 at zoo, sanctuaries or in the wild.  “At this time, Chimp Haven has chosen not to move forward with the vaccination, but we’re continuing to keep our options open,” says Raven Jackson-Jewett, director of veterinary care and the attending veterinarian at Chimp Haven.

Chimp Haven and several other sanctuaries cited the experimental nature of the Zoetis vaccine and said they wanted to learn more about its efficacy. The vaccine, which was first developed for use in cats and dogs, has only been authorized for experimental use in animals. Zoos and sanctuaries must individually request approval from the U.S. Department of Agriculture (USDA) and state veterinarians to receive a dose of each vaccine, which Zoetis then donates.

Zoetis is currently working toward getting a conditional USDA license to use its vaccine in mink, which in some countries are farmed in large numbers for their fur. (The company says a U.S. license would likely make it easier to sell the vaccine abroad). Mink are known to contract SARS-CoV-2 and have been shown to transmit it to people, leading to outbreaks and the culling of many of them on Dutch farms. The company is planning challenge trials in the animals—vaccinating them and deliberately exposing some to the coronavirus—to test the vaccine’s protection and how well it works against variants of COVID-19.

Mahesh Kumar, the senior vice president of global biologics research and development at Zoetis, says the company is confident its vaccine is safe for animals. Still, Kumar acknowledges the vaccine’s efficacy in different species remains unclear.

Great ape sanctuaries outside of the United States are also pondering whether to vaccinate their animals, although Zoetis shot isn’t yet available in other countries. Members of the Pan African Sanctuary Alliance (PASA), an organization that works with 23 primate sanctuaries across 13 African countries, have expressed interest in a COVID-19 vaccine for their animals, according to the group’s director, Gregg Tully. “We’re open to learning more about vaccines,” Tully says. “Whether they decide to vaccinate their primates depends on a lot of factors.”

One may be Africa’s need to prioritize vaccinating people. Fueled by the Delta variant, COVID-19 cases and deaths have soared in Africa over the past several months, and less than 1.5% of people on the continent are fully vaccinated, according to a recent World Health Organization update. “The focus now is on trying to vaccinate the staff and people surrounding the animals as a way to minimize the risk,” Tully says. “In Africa, right now, the availability of vaccines is increasing but it’s still frighteningly low.”

originally published at Science

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