A leading US government agency has defended previous funding for research into bat coronaviruses in China, saying the pathogens in question could not have caused the Covid-19 pandemic . Funds from the National Institutes of Health – which were given to the US non-profit EcoHealth Alliance for research conducted with the Wuhan Institute of Virology – have come under increasing scrutiny in light of the theory that the virus could have escaped from the Chinese lab and questions about whether the genetic manipulation of viruses played a role. But an analysis by the National Institute of Allergy and Infectious Diseases (NIAID), a branch of the NIH, said the viruses in question were too distantly related to Sars-CoV-2 to have played any part in its emergence. How Chinese red tape stopped US scientists getting early virus access “The chimeric [engineered] viruses that were studied … were so far distant from an evolutionary standpoint from Sars-CoV-2 that they could not have possibly been the source of Sars-CoV-2 or the Covid-19 pandemic,” the analysis, published on the NIH’s website on Wednesday, said. The release came just days after a group of 10 Republican senators introduced a bill to place a new moratorium on federal funding for “risky research on potential pandemic pathogens”, citing concerns about previous research funding for “foreign entities” and pointing to the EcoHealth grant. The NIH gave EcoHealth US$3.1 million over five years from 2014 to study the risk of a bat virus spilling into humans in China, as happened in the 2002 outbreak of severe acute respiratory syndrome. A subsequent grant was pulled in 2020. As a grant partner, the Wuhan Institute of Virology received between US$120,000 and US$150,000 a year from EcoHealth over this period. The work funded included experiments using genetic engineering and mice with human-like cells to test if features of newly discovered bat viruses were potentially dangerous to humans. The virus used as a framework for the experiments was not known to infect people, and the tests in cells and mice relied on “techniques common in virology”, the latest statement said. Controversy around EcoHealth’s collaboration with the Wuhan lab grew last month after The Intercept investigative news site published some of the non-profit’s grant reports to the NIH, which it obtained after a freedom of information request. Some scientists said data included in the documents indicated the experiments enhanced the viruses’ ability to grow in mice. They argued this could be considered “gain of function research”. Coronavirus: US cables highlight concerns over Wuhan laboratory Such research, when applied to make certain human viruses more transmissible or severe, was subject to a US funding moratorium between 2014 and 2017. The Republican senators’ bill calls for a further pause in funding for this type of research. NIAID director Anthony Fauci has repeatedly said that experts evaluating the research had concluded it was not gain of function. He has also dismissed suggestions US-funded research had a role in the start of the pandemic. The NIAID analysis does not address the gain-of-function question and instead focuses on the differences between Sars-CoV-2, which is thought to have originated in bats, and its closest known relatives. “Experts in evolutionary biology and virology have made it clear that even the closest known relatives of Sars-CoV-2, which were not studied under the EcoHealth Alliance grant, are evolutionarily too distant from Sars-CoV-2 to have been the progenitor of the COVID-19 pandemic,” the analysis said, noting fieldwork was under way to find closer relatives. International efforts to find the origins of the virus have stalled. The World Health Organization has been forming a new team to guide the research, but Beijing has rejected its proposals to evaluate whether the initial spread of Covid-19 could have been linked to a lab in Wuhan – a theory the Chinese authorities have rejected and which most scientists regard as less likely than a natural origin. A US intelligence assessment released in August could not reach a conclusion about whether the virus had its origins in a laboratory accident or natural transmission, but it did say that the virus was “probably not genetically engineered”.