COVID-19 'Lab Leak Theory'... US Study Finds 'Very Unfortunate Coincidence' Likely

US Research Team Analyzes Evolution of Seven Viruses
No Significant Genetic Changes in COVID-19 Before Human Transmission

A new study has found no evidence that the COVID-19 virus was created or leaked from a laboratory in China. The researchers analyzed several viral outbreaks, including COVID-19, and concluded that in most cases, viruses were transmitted to humans from animals by chance and then spread after adapting to humans.

Recently, The New York Times reported on the findings of a University of California, San Diego research team, published in the journal Cell. The study compared several viral outbreaks, including COVID-19, and found that in most cases, viruses were transmitted to humans from animals by chance and then spread after adapting to humans.

January 2021, the World Health Organization (WHO) COVID-19 origin investigation team visited a hospital in Wuhan, China. Yonhap News

The research team compared seven viral outbreaks that have occurred in recent decades. The analysis included COVID-19, Ebola, and influenza.

The results showed that, in most cases, no significant genetic changes appeared before the virus was transmitted to humans. The viruses circulated among animals and, through a chance event, were transmitted to humans, after which they acquired the ability to spread between people.

Joel Wertheim, a professor at the University of California, San Diego who led the study, said, "This pattern is observed repeatedly."

The researchers analyzed the genetic information of the viruses to reconstruct the evolutionary processes of each virus. In particular, they tracked which mutations the viruses acquired before causing large-scale outbreaks and what changes occurred after they spread to humans.

"Better adaptation for transmission among human hosts"… Analysis of the 2009 pandemic case

The research team first analyzed the 2009 novel influenza (swine flu) outbreak. At that time, a new flu virus emerged in North America, infecting about one quarter of the global population and causing approximately 230,000 deaths.

This virus is known to have originated from pigs. Influenza viruses circulating among pigs continue to mutate; some changes reduce transmissibility, some favor survival, and some have little impact.

The strain of the virus that was transmitted to humans in 2009 had already diverged into its own evolutionary lineage at least 10 years prior. However, it exhibited typical evolutionary patterns up until its transmission to humans. The patterns of mutation emergence and disappearance were also not significantly different from those of other flu viruses circulating among pigs.

However, after transmission to humans, the situation changed significantly. Since 2009, this virus rapidly accumulated new mutations. While such mutations may have hindered viral replication in pigs, after entering humans—a new host—the virus evolved in a direction better suited for transmission between people.

Virus. Pixabay

The research team also analyzed the 2013 Ebola outbreak in West Africa and the 2022 mpox outbreak using the same methodology. Ebola is thought to have originated from bats, while mpox is believed to have originated from animals such as monkeys and squirrels.

The results were similar. Before transmission to humans, the viruses did not show significant evolution, but once they entered human populations, rapid genetic changes occurred. Professor Wertheim commented, "The moment a virus enters humans, it encounters a completely new environment."

"COVID-19 also likely a 'chance transmission'"

The researchers stated they found no evidence of significant genetic changes in the COVID-19 virus before it was transmitted to humans. The virus circulated among bats, accumulating mutations like other coronaviruses, and only after transmission to humans did it undergo rapid change. Professor Wertheim said that the COVID-19 pandemic was most likely "the result of a very unfortunate coincidence."

Previously, an expert group dispatched by the World Health Organization (WHO) to investigate the origins of COVID-19 stated last month, "The SARS-CoV-2 virus originated from bats and was most likely transmitted to animals sold at markets in Wuhan."

This content was produced with the assistance of AI translation services.