An international expert panel on Covid-19 has called for continued investigation into the origins of the coronavirus, saying the pathogen could have either spilled over from nature or an infection of a laboratory worker. In its final report this week, the Lancet Commission on Covid-19 led by Columbia University professor Jeffrey Sachs said the virus could well have had a natural origin, but the commission could not rule out it could have passed to humans during laboratory research in Wuhan, the Chinese city where the virus was first detected, or elsewhere. Even if it was a laboratory leak , it could well be a natural virus or a bioengineered virus, the report said, adding investigation and better monitoring of such research was needed. “The [World Health Organization], governments, and the scientific community should intensify the search for the origins of Sars-CoV-2, investigating both a possible zoonotic origin and a possible research-associated origin,” it said. “Because beta coronaviruses related to Sars-CoV-2 are found across East Asia, the search for a natural source of Sars-CoV-2 should continue with high focus and intensity, as the eventual discovery of a natural reservoir of the virus might occur only after years of searching, and quite possibly outside of China.” The commission was convened by the medical journal the Lancet and took two years to compile input from more than 170 scientists and researchers. Its final report was released on Wednesday after a series of preliminary reports. The commission aims to make suggestions on better policies and global cooperation and it is not an investigative body or a body of biomedical specialists. Sachs earlier drew ire from Western media when he said the virus could have come from a US laboratory, a claim picked up on by Chinese media. The report on Wednesday said more research on the possibilities was needed. “No independent, transparent, and science-based investigation has been carried out regarding the bioengineering of Sars-like viruses that was under way before the outbreak of Covid-19,” the report said. Lancet Covid-19 Commission head denies China’s claims of US pressure “Independent researchers have not yet investigated the US laboratories engaged in the laboratory manipulation of Sars-CoV-like viruses, nor have they investigated the details of the laboratory research that had been under way in Wuhan.” A trip by WHO inspectors to Wuhan in early 2021 shed little light on the issue and was criticised by Western media and scientists as failing to conduct independent research. China has strongly rejected the laboratory leak theory, and sought to point the finger at the United States and its researchers. The Lancet report said all theories should be considered and independently researched. Although the origin of Covid-19 remains unclear, the pandemic serves as a reminder of the need for better monitoring of virus manipulation through “gain-of-function” research, according to the commission. “Many scientists have warned of the increasing risks of under-supervised and under-regulated genetic manipulation of Sars-CoV-like viruses and other potential pandemic pathogens,” the report said. “There is currently no system for the global monitoring and regulation of gain-of-function research of concern.” It said that so far there was no evidence that Beijing knew of the outbreak until late December, but there may have been delays in local authorities reporting the outbreak to the national authorities. The report also criticised the WHO for being too conservative and slow in pointing out the risk of asymptomatic and airborne transmissions, as well as failing to call for mask wearing during the early stage of the pandemic. In the early days of the pandemic, the WHO said droplets were the major means of transmission while the chance of airborne transmission was low. “In the swirl of uncertainty during the Covid-19 outbreak, the WHO … repeatedly erred on the side of reserve rather than boldness,” the report said. The WHO said it made a timely response. Human cost of China’s zero-Covid policy measured in stress, anxiety The Lancet report also said the suppression strategy adopted by many Asian and Pacific countries, including China, had been useful in lowering the number of deaths. But such a strategy, which relies on contact tracing, quarantine and testing to keep the number of cases low, should only buy time for an exit strategy, such as mass inoculation, it said. The authors did not say directly whether China should continue to hold on to its zero-Covid strategy. Two Chinese experts, Wang Chen from the Chinese Academy of Medical Sciences, and Xue Lan from Tsinghua University, are among the authors of the report.