Photo by CDC from Pexels

More than 219 million cases, almost 4.55 million deaths, and one virus, yet the world continues asking the very same questions. Almost two years have passed since the coronavirus started spreading like fire around the globe. COVID-19 single-handedly destroyed economies, social norms, and life as we know it all while remaining the perfect mystery for conspiracy theorists to feast upon. Despite many ongoing investigations and many theories, the world still doesn’t know the origin of the coronavirus. 

“There’s a popular perception that we need some kind of justice or explanation and somebody needs to answer for this pandemic. But the real reason why we need to figure out the origin is so that it can inform our efforts to prevent another pandemic like this from happening,” says Angela Rasmussen, a virologist at the center for global health science and security at Georgetown University Medical Center. 

Direct animals to humans spillover

The first theory behind the coronavirus is plain and simple, and the world health organization asset it as possible to likely. In a way, it is the same origin story of HIV, influenza epidemics, and previous Ebola outbreaks. SARS-CoV-2 already started as an existing virus in animals, an accident happened, a human got infected, then absolute chaos.

“So what you have to worry about then is how did it get from bats to humans?” David Robertson, head of viral genomics and bioinformatics at the University of Glasgow, says. “Did somebody go into an area, get infected, and then get a train to Wuhan?”

A direct bat to human transmission is very likely. People living near bat caves in southern China’s Yunnan Province already have antibodies to bat coronavirus. The real mystery regarding this theory takes a geographical status. The bat caves of Yunnan and the Wuhan provinces are separated by 100 miles. So how did a virus that supposedly spilled to humans directly from Yunnan bats get discovered in Wuhan instead? Further, scientists are yet to find the kind of bat responsible since it would take decades for related bat coronavirus to evolve into SARS-CoV-2.

Animal to human spillover through an intermediate host

This second theory has precedences, and the WHO classifies it as likely to very likely. It mainly revolves around a natural chain of events that accidentally led to this disaster. Instead of a bat-human direct spill, the virus is transmitted from the bat to another animal, like a mink or a pangolin since they have regular human contact. That animal in return spread the virus to humans.

This theory not only explains how the virus got in contact but also how it mutated and became harmful. It is also the same way the previous coronavirus was able to spread. For example, the ruling theory for the SARS 2002 epidemic is the virus’s transmission from bats to palm civets, then to humans. 

Though most likely, the WHO wasn’t successful in identifying such animals carrying the virus, despite analyzing samples from thousands of farmed animals across China.

“That’s a fraction of the animals that are farmed or captured or transported for this purpose in China,” says Daniel Lucey, an adjunct professor of infectious diseases at Georgetown University Medical Center. “I think we haven’t done anywhere near enough sampling.”

Laboratory leak

The last theory is the one conspiracy theorists are rallying behind, even though the WHO asset it as extremely unlikely. Until now, evidence with and against a laboratory spill in Wuhan remains thin. This theory is divided into two assumptions. The first is that a researcher was accidentally infected in the lab, while the second is researchers intentionally manipulated a coronavirus strain. Since genetic evidence shows that the virus arose naturally, many experts debunked the second assumption. However, speculation around the first assumption is still circulating. 

“All scientists need to acknowledge a simple fact: Humans are fallible, and laboratory accidents happen — far more often than we care to admit. Several years ago, an investigative reporter uncovered evidence of hundreds of lab accidents across the United States involving dangerous, disease-causing microbes in academic institutions and government centers of excellence alike — including the Centers for Disease Control and Prevention and the National Institutes of Health” explains David Relman, professor of microbiology and immunology.

References:
Gill, B. V. (2021, July 10). Covid origins: Scientists weigh up evidence over virus’s origins. BBC News. https://www.bbc.com/news/science-environment-57782955Goldman. (2021). 5 Questions: David Relman on investigating origin of coronavirus. Stanford. https://med.stanford.edu/news/all-news/2021/05/david-relman-on-investigating-origin-of-coronavirus.htmlMcKeever, A. (2021, June 3). We still don’t know the origins of the coronavirus. Here are 4 scenarios. Science. https://www.nationalgeographic.com/science/article/we-still-dont-know-the-origins-of-the-coronavirus-here-are-four-scenariosNature Editorial. (2021). The COVID lab-leak hypothesis: what scientists do and don’t know. Nature. https://www.nature.com/articles/d41586-021-01529-3?error=cookies_not_supported&code=8a5d40bb-8038-49f6-9dbd-425c1e1b7cb4