Giant pandas and rhinos have joined the ranks of animals that may be able to contract COVID-19.

In a peer-reviewed paper published Thursday in the scientific journal Proceedings of the National Academy of Sciences, researchers from Tsinghua University in Beijing, Fudan University in Shanghai, and Westlake University in Hangzhou identified an expanded list of animals — at least 44 species — that could be susceptible to the coronavirus.

After screening nearly 300 animal species including birds, reptiles, mammals, amphibians, and fish, they identified 80 — all mammals — with several protein elements important to viral binding and entry during human infection.

Ding Qiang, a virologist at Tsinghua University who led the study, told Sixth Tone that it’s unclear why only mammals possessed the type of protein that allowed the coronavirus to latch on. “But our research shows that some previous hypotheses, like salmon contracting the virus, are incorrect,” he said.

Of the 80 potential hosts, the team chose 48 species that are endangered or often in close contact with humans for further research. They found that 44 animals, including gibbons, rabbits, pigs, giant pandas, and rhinos, could become infected with the coronavirus.

A key finding, the researchers said, was that being genetically closer to humans didn’t seem to make species more likely to contract COVID-19. While animals like cats are highly susceptible to infections, New World monkeys — a group of primates native to the Americas that includes marmosets and squirrel monkeys — have small genetic mutations on the key protein that stop the virus from entering their cells.

“We don’t know what kind of pressure they underwent during evolution to result in these changes,” Ding told Sixth Tone. “I’m not an expert on evolution, but I’m amazed.”

In the last two decades, there have been three major coronavirus outbreaks. For SARS and MERS, palm civets and camels are generally accepted as the intermediate hosts — the animals that passed the respective viruses to humans. While many scientists suspect that SARS-CoV-2 originated in bats, the intermediate host or hosts are still unknown, which is a source of great concern to those seeking to stop such viruses from spreading to humans again in the future.

“Based on the result of this study, if we want to completely wipe out the virus, we need to consider the possibility of transmission between animals and humans,” Ding said.

With SARS-CoV-2 now appearing to affect more animals than previously thought, the researchers stressed the importance of cracking down on the trade and consumption of illegal wildlife, as well as surveilling animals that come into close contact with humans.

Additional reporting: Ye Ruolin; editor: Ye Ruolin.

(Header image: People Visual)