Animals carrying coronaviruses related to the one that causes COVID-19 may infect hundreds of thousands of people annually across China and Sourtheast Asia. According to a study emphasizing the ongoing pandemic threat from spillover events, an average of 4,00,000 such infections occur annually. The study, reported by the Bloomberg says most of such infections go unnoticed because they cause mild or no symptoms. Moreover, the infections are not easily transmitted between people.
The study was conducted by researchers with the EcoHealth Alliance and Singapore's Duke-NUS Medical School and says each spillover represents an opportunity for viral adaptation that could lead to a COVID-like outbreak.
The question of where and how the virus that causes Covid emerged has become particularly contentious, with some leaders blaming a hypothetical leak from a lab in Wuhan, China that studies the pathogens. The research, supported by the U.S. National Institute of Allergy and Infectious Diseases, builds on evidence that bats are the main host-animals for viruses like SARS-CoV-2 and that people living near their roosts are especially vulnerable.
"This is probably the first attempt to estimate how often people are infected with SARS-related coronaviruses from bats," said Edward Holmes, an evolutionary biologist at the University of Sydney who wasn't involved in the research. Humans are continually exposed to bat coronaviruses, he said.
"Given the right set of circumstances, one of these could eventually lead to a disease outbreak."
Almost two dozen bat species that can be infected by coronaviruses dwell in an area of Asia more than six times the size of Texas, with southern China and parts of Myanmar, Laos, Vietnam and Indonesia deemed the riskiest for spillovers.
China's stand on Wuhan lab leak theory
In August this year, China had opposed next-phase COVID-19 origins-tracing, saying that it is "inappropriate" that the World Health Organization (WHO) came up with the second phase of the study that focused on a lab-leak theory. In recent months, the lab-leak theory has gained great traction after the Biden administration pushed for a fresh intelligence probe into the virus origin.
"The next-phase COVID19 origins-tracing should be carried out worldwide in countries where horseshoe bat and pangolins reside, and which supply Wuhan Huanan market through cold-chain logistics," said Liang Wannian, a Chinese expert in the WHO-convened joint team on origins tracing, as quoted by Global Times.
"It's unacceptable and inappropriate that WHO came up with 2nd-phase of COVID19 origins-tracing that focused on a lab-leak theory, classified as extremely unlikely in the 1st-phase study, which ignored evidence and did not consult member states," said China's Health Commission official.
This came hours after the WHO had said the next step in the search of the origins of COVID-19 will be the creation of a new advisory group that will develop a global framework to study pathogens with pandemic potential.