It’s that age-old question that sparked controversies ever since the coronavirus spread worldwide in 2020. Where did it come from and how did it get started? Two scientists claimed on Sunday that “damning” evidence clearly implies COVID-19 is a man-made pathogen, designed in a lab for optimum infectivity prior to striking the outdoors to fatal effect.

New evidence has reignited interest in this putative source of the coronavirus, which researchers still believe is implausible but worth examining.

Dr. Steven Quay and Richard Muller, writing in The Wall Street Journal, cited two major pieces of data to support the notion, which has proliferated after years of being dismissed as nothing more than hearsay.

The foremost is about the essence of acquiring research studies, which involves microbiologists manipulating a virus's DNA in order to change its qualities, such as rendering it more contagious or fatal.

According to Quay and Muller, among the 36 potential genome pairings that might yield two arginine amino acids in a succession — enhancing a virus' lethality — CGG-CGG, or double CGG, is the most widely employed in gain-of-function studies.

“The insertion sequence of choice is the double CGG,” said Quay. “That’s because it is readily available and convenient, and scientists have a great deal of experience inserting it,” the researchers added.

They wrote that an additional advantage of the double CGG sequence over the other 35 options is that it provides a valuable beacon that allows scientists to "track the insertion in the lab.”

The double CGG sequence has never been detected naturally in the whole group of coronaviruses that includes CoV-2, which causes COVID-19.

However, it was discovered in CoV-2, which Quay and Muller described as a "damning fact."

The researchers said in the journal that supporters of animal origin must explain why the new coronavirus chose its least preferred pairing, the double CGG, when it mutated or recombined.

“Why did it replicate the choice the lab’s gain-of-function researchers would have made?” they raised. "At the minimum, this fact — that the coronavirus, with all its random possibilities, took the rare and unnatural combination used by human researchers — implies that the leading theory for the origin of the coronavirus must be laboratory escape,” they added.

According to National Geographic, many experts, many of whom participated with the World Health Organization's months-long probe, feel the most rational answer is that it passed from an animal to a human—possibly from a bat to a human directly or via an intermediary host. Certain viruses propagate by animal-to-human transmission; at least two other coronaviruses, SARS and MERS, were disseminated by animal carryover.

Meanwhile, some argue it's worthwhile considering whether SARS-CoV-2 got out of the Wuhan Institute of Virology, which has been studying coronaviruses in bats for over a couple of years.

COVID-19 Laboratory Representation Image. Two scientists claimed on Sunday that “damning” evidence clearly implies COVID-19 is a man-made pathogen, designed in a lab for optimum infectivity prior striking the outdoors to fatal effect. Creative Commons Pixabay