The World Health Organization headquarters in Geneva, Switzerland. (PHOTO: XINHUA)

"The theory that the virus escaped from the Wuhan lab is not credible," a French biosecurity expert who had monitored the construction of the Biosafety level 4 (BSL-4) laboratory of the Wuhan Institute of Virology has said recently in reference to COVID-19.

The lab "was built under the close cooperation between China and France," and "there is no doubt about its compliance with the highest international biosafety standards," Gabriel Gras said.

"I am not speculating, I prefer to rely on facts," said Gras in an interview with Xinhua on Sunday amid growing speculation about a possible laboratory accident that could have triggered the COVID-19 pandemic.

During his stay in China, Gras participated in implementing the 2004 Sino-French Cooperation Agreement in Prevention and Control of Emerging Infectious Diseases, and supervised the construction and accreditation of the Wuhan Institute of Virology's BSL-4 laboratory in 2017.

The construction and operation of the Wuhan lab conform to very strict standards, he said. "It was my job to check all of this, and there was no doubt about the level of safety of the facility."

Gras also noted that coronaviruses, including the SARS-CoV-2 virus, "doesn't need to be dealt with in a BSL-4 lab" considering the high cost of operating a BSL-4 lab.

Biosafety levels, which are a set of biocontainment precautions required to isolate dangerous biological agents in an enclosed laboratory facility, range from the lowest BSL-1 to the highest BSL-4. A BSL-4 laboratory works with the most dangerous agents that can generate fatal diseases in humans such as Ebola hemorrhagic fever.

"It is very expensive to operate a BSL-4 lab, in money but also in time, since the experiments take longer to set up due to safety constraints such as wearing a high-pressure diving suit," Gras explained, saying that it's "just common sense" that they don't work in BSL-4 labs with BSL-3 pathogens any more than they do in BSL-3 labs with BSL-2 pathogens.

Coronaviruses are mostly classed at BSL-2, sometimes at BSL-3, such as SARS-CoV of 2002, MERS-CoV of 2012, and finally SARS-CoV-2 of 2019, but never at 4, Gras said.

The classifications of pathogens and guidelines on the conditions of their culture are public and available online, and have been established by the World Health Organization and relevant national authorities.

"Using a BSL-4 to work with a coronavirus is like using a 20-ton crane to move a 30-kg refrigerator. It would be completely illogical," said the French expert, adding that "the theory of leak of the SARS-CoV-2 virus from the Wuhan BSL-4 lab is against common sense." 

(Source: Xinhua News Agency)