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Why the search for animals harbouring coronavirus is a matter of life and death

Ever since the coronavirus started spreading around the world, scientists have worried that it could leap from people into wild animals. If so, it might lurk in various species, possibly mutate and then resurge in humans even after the pandemic has subsided. Because it is believed that animals brought the virus to us in the first place, resurfacing through animals once more would bring the tale of SARS-CoV-2 full circle.

According to the scientific publication Nature, “strong evidence suggests that the virus originated in horseshoe bats,” possibly hitching a ride on other animals before infecting people. In the current stage of the pandemic, with hundreds of thousands of confirmed COVID-19 infections every day, people are still driving transmission of the virus. But years from now, when community spread has (hopefully) been suppressed, a reservoir of the virus in free-roaming animals could become a recalcitrant source of new flare-ups, and that’s pretty worrying.

When, almost a year into the pandemic, a seemingly healthy wild mink tested positive for SARS-CoV-2 in Utah, no free-roaming animal was known to have caught the virus before, although researchers had been watching for this closely. But wild animals are not the only ones to have drawn scrutiny. Studies have shown that SARS-CoV-2 can infect many domesticated animals, from cats and dogs to pumas, gorillas and even snow leopards in zoos, as well as the infamous farmed minks in Denmark. Previous outbreaks in mink farms have already shown that infected animals can pass the virus back to humans.

Although these cases have raised concerns, researchers are less worried about viral outbreaks in domestic and farmed animals because such eruptions can be kept in check through quarantining, vaccination and culling, explains Nature. If the virus spreads in wild animals, however, it will be much more difficult to control.

Just like it mutated among humans, the virus could evolve as it circulates among animals, possibly in ways that threaten the efficacy of vaccines or make the pathogen more deadly and infectious to people. “Not to sound any alarms, but everything we don’t want to see with this virus seems to happen,” says Arinjay Banerjee, a coronavirus researcher at McMaster University in Hamilton, Canada.

Over the past year, scientists have tried to gauge exactly how grave the risks are. Global efforts are underway to survey wildlife and catch ‘spillovers’ as soon as possible. Researchers are testing animals from homes, zoos, shelters, veterinary clinics, farms and their surroundings. If any positive cases are detected, countries immediately notify the World Organisation for Animal Health (OIE), which is based in Paris.

On top of that, scientists have used computational models and studied cells and whole animals to identify the species most vulnerable to infection. In one year, they’ve collected as much data about the susceptibility of different species to SARS-CoV-2 as was accumulated over the past 50 years for influenza, says Martin Beer, a virologist at the Federal Research Institute for Animal Health (FLI) in Greifswald, Germany.

If you’re already panicking about potentially having to undergo more lockdowns in the next few years, it should be said that animal infections are rare, and some researchers are reassured by the data collected so far. However, others are more cautious. The virus is known to infect a wide range of animal species, which combined with the large number of infected people, means that, in principle, the virus has had millions of opportunities to jump from people to animals. And of course, many of those jumps could be missed by scientists.

Which animals are primary suspects?

At the beginning of the pandemic, pigs were top of the watchlist. They are known to incubate other viruses, such as influenza, and they live in huge numbers in close proximity to humans—some 300 million pigs are farmed in China, where the pandemic began.

Pigs can also host coronaviruses. In 2018, researchers described a new bat coronavirus that had killed some 25,000 pigs in southern China. However, when researchers began artificially infecting pigs and piglets with SARS-CoV-2, they found that it did not replicate well. These studies suggest that pigs are largely resistant to infection with the virus.

Then, bats became the centre of attention. They are the purported source of SARS-CoV-2, and researchers worried that the virus could spread into new bat populations. In April 2020, the US Fish and Wildlife Service advised scientists to suspend all research that involved capturing and handling bats. As with pigs, however, the results of studies into bats have been generally reassuring.

So, researchers began turning their attention to other animals that are genetically closely related to people, live in close contact with humans or are known sources of other viral outbreaks. Laboratory experiments have ruled out a horde of potential hosts—raccoons, for example, and important livestock such as cows, ducks and chickens, which all seem resistant to infection.

But the experiments have found many animals that can harbour the virus and pass it on. Among them are ferrets, cats, raccoon dogs, white-tailed deer and several species of monkeys. Infected animals that are sociable (in a herd or with humans) pose a larger risk than lone roamers.

A growing number of real-world studies are beginning to reveal the true risk that animals pose. As more reports surfaced of pets who had caught COVID-19 from their sick owners, researchers took an increased interest in cats, which are often free to slink between households and mingle in the wild. However, their possible role in COVID-19 transmission remains a subject of debate.

For now, fast-spreading variants that were first identified in the UK, South Africa and Brazil have not yet been tested for their ability to infect animals. The new variants’ global spread increases the possibility that house mice, and perhaps also rats, will acquire the infection from people and contaminated environments such as sewers, leading many scientists to expect other ‘surprises’ like the previous mink crisis.

COVID-19 mutations: what does the future really look like?

It’s very common for coronaviruses (CoV) to mutate—they are a family of viruses that cause respiratory and intestinal illnesses in humans and animals, and range from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). News of the coronavirus COVID-19’s mutations spreading has undoubtedly caused fear, but to scientists it should be an unsurprising feature of what we all know as COVID-19. Which mutations are currently causing trouble? And how will they affect our future?

COVID-19 mutations

New strains of the novel coronavirus are spreading all over the world. In the US, the strains all have at least one thing in common: ‘N501Y’, which is making the virus more likely to infect our cells. There are three major new strains so far, and two of the three strains—the ones from the UK and South Africa—evolved their N501Y mutations independently. In other words, the two strains may not be directly related. One didn’t evolve into the other, and that’s worrying.

According to the Daily Beast, it’s unclear whether the new strain from Brazil also mutated N501Y on its own “but the separate appearance of even two similar strains is cause for concern.” Trevor Bedford, a professor of vaccines and infectious diseases at Fred Hutchinson Cancer Research Center in Seattle tweeted that “There is substantial convergent evolution happening.” and continued that “The fact that we’ve observed three variants of concern emerge since September suggests that there are likely more to come.”

How do mutations come to be?

Each coronavirus contains nearly 30,000 letters of Ribonucleic acid (RNA), which are molecules that play an essential role in coding, decoding, regulation and expression of genes. This genetic information allows the virus to infect cells and hijack them to make new viruses. One infected cell will build new viruses, and occasionally, it makes tiny copying errors along the way—which are called mutations.

These mutations can be tracked as they are passed down through a lineage, but a group of coronaviruses that share the same set of distinctive mutations is called a variant. According to The New York Times, “If enough mutations accumulate in a lineage, the viruses may evolve clear-cut differences in how they function. These lineages come to be known as strains. COVID-19 is caused by a coronavirus strain known as SARS-CoV-2.”

These variants have become increasingly prevalent as the SARS-CoV-2 (let’s just call it COVID-19) has spread around the world. When a vaccine has been produced to fight one variant, and another pitches up, the worry is that the vaccine won’t be attuned to fight off both variants.

The Financial Times wrote that “During the first phase of the pandemic in the first half of 2020, Sars-Cov-2 was spreading through a previously unexposed population, so there was little Darwinian pressure on the virus to evolve mutations to evade the attention of the immune system. This has now changed.” Epidemiologists reported to the magazine that “the moment of maximum danger may come within the next few months when a larger number of people have been infected or vaccinated but many still remain unprotected. Then there would be enough community transmission to generate new variants and enough immunity to create an advantage for variants that can escape it.”

N501Y, which is what is common in two out of three of the variants currently, affects the spike protein which helps the virus grab onto and enter our cells. The Daily Beast said that “It seems N501Y makes the spike protein ‘grabbier.’ Given roughly equal exposure to the older strain of SARS-CoV-2 and one of the new strains, the new strains could be more likely to make you sick.”

The virus effectively seems to be fighting back with new mutations that could have the potential to allow its spread even faster than before. COVID-19 (or SARS-CoV-2) has mutated previously without actually producing significant new strains, however this changed in September 2020. The B.1.1.7 was found in the UK, and the B.1.351 in South Africa, then the P.1 strain in Brazil. According to The Daily Beast “There are signs that B.1.1.7, B.1.351, and P.1 are more transmissible than the baseline novel coronavirus—and might also partially resist the immunity-inducing effects of the new COVID-19 vaccines.”

In December of 2020, the B.1.1.7 reached the US, and now P.1 and B.1.351 have also been found throughout the country. Studies indicate that the vaccines in the US are less effective against new strains. In South Africa, the AstraZeneca vaccine has shown ineffectiveness against mild and moderate cases of the strain.

What does our future look like?

Scientists are learning about the mutations of COVID-19, and N501Y. Jennifer Reich, a sociologist at the University of Colorado Denver specialising in vaccination, told The Daily Beast that “Our best defence against any variant is to support science that can be proactive in genetically sequencing viruses.”

Everyone wants to go back to a life pre-COVID-19, but unfortunately, the longer the virus is in circulation, the more opportunity it has to mutate. Aimee Bernard, a University of Colorado immunologist also spoke to The Daily Beast and stated that “If we don’t continue to follow the necessary precautions to stop the spread of the virus and all get vaccinated, the virus will continue to do what it does best—survive, mutate, and spread to more people.”

Our part to play in it being said, governments are setting out testing facilities to increase monitoring of the variants. In the UK, ‘surge testing’ has been rolled out in neighbourhoods where the N501Y variant has been found, and everyone in those places are getting asked to get tested, regardless of whether they have symptoms or not. The samples are then sent off for genomic sequencing, which in turn will help with vaccination advancements.

The US is preparing plans for updating vaccines as well if the new variants surge, but for now, we all have to sit tight, even if (physically) in separate. Science is the only way out of this, one way or another. There is evidently no way of truly knowing what life has in store for any of us, but that being said, when you understand something, you may be less afraid of it.