the evidence supporting a lab league for now is all circumstantial. Starting with the labs location the BSL four lab or biosafety level four is about 25 miles from the wanton seafood market. That is where many of the first covid 19 cases initially emerged. I don't think anyone would disagree that the major first amplification occurred in Wuhan. The chinese have pushed back against the claim the virus was engineered. But if the first amplification was from a lab that would suggest either a lab worker unknowingly got infected or that the virus was isolated and were manipulated in a lab and somehow got out sparking concern over the type of research that might have been taking place here. I'm not saying that they lead to this outbreak or pandemic by any means, but it's simply the kind of work that I think we as a scientific society need to think much more clearly and more deliberately about before we undertake it CNN spoke with a source directly involved with the construction of the BSL four using their insight along with information published by the chinese before the outbreak, here's what we know planning and construction of the BSL four started in 2000 and three in 2018. It officially became operational, it's located on the sprawling fenced in Wuhan Institute of Virology campus. The building containing the lab since separate four levels make up the structure at the top, a sophisticated air purification system at the bottom and underneath the lab decontamination equipment that allows for safe sewage disposal Level two. This is where the research takes place, there are separate entrances and exits along with dedicated dissection rooms by restoring facilities and multiple labs for distinct animal and cellular level. Research french engineers helped in the planning and the construction but one source tells us the chinese were initially resistant in adding some basic safety features due to the high cost of some equipment such as multiple chemical decontamination showers but that they eventually relented adding them. Some have also questioned the lab staff's training. A 2018 diplomatic cable sent by US officials who made a site visit stated that quote, the new lab has a serious shortage of appropriately trained technicians and investigators needed to safely operate this high containment laboratory. The cable went on to say that the University of texas Medical branch in Galveston U. TMB has scientific collaborations with Wi V which may help alleviate this talent gap over time. Scott weaver of U. TMB tells me the collaborations with the Wuhan Institute of Virology or Minor and did not involve coronavirus research. He has not visited Wuhan's BSL four lab but stresses that the training required for such a lab is extensive. Typically the scientists are wearing space suits. These are suits that are very expensive, very well designed to be airtight and they're pumped full of filtered air such that even if an accident occurred in the lab and there was some kind of a spill in an aerosol would be created. That space suit would prevent that aerosol from entering the breathing space of the scientists to infect them. But other red flags came from the chinese themselves, including Wi ves director wang Jiaming Who in 2018 co authored a paper pointing out safety issues across all biosafety labs in China warning in part that there was a lack of enough operable technical standards. But ultimately, many international experts viewed. The Wuhan Institute of Virology is BSL four as one of the most sophisticated in the world and its researchers more than competent who had a first class facility, high class virologists and well trained staff. You put all of that together and you'd say, well I can't exclude a lab accident. Um it doesn't seem likely. It also does not rule out the possibility of a leak from another lab in Wuhan. We drove by it last year. Okay, there you can see right here, this is Wuhan Center for Disease Control. This is one of the labs within Wuhan and of course not too far from the market either. Located just a couple of blocks from the wanton seafood market, in fact, inside lower level biosafety labs that likewise involved the study of bats and corona viruses. Still, there is one thing lacking in the search for an origin that is full transparency from in collaboration with the chinese. Unfortunately, it's been very disappointing to see that the chinese government has not been very forthcoming with some of the critical information about the very early stages of the outbreak. China has shut the door on future visits by the W. H. O. Chinese officials believe the origins investigation has become politically manipulated by the US. Especially given biden's order for an intel community review, One that focuses in part on the lab leak theory. We do need to have the evidence and the very people who are calling for it have precluded that from happening. And the longer it takes, the more difficult it's going to be to get a complete picture of what happened. Maybe never. It may be too late now. Without any concrete proof, experts warn that prematurely concluding COVID-19 started from a lab leak might leave the world and scientific community divided over geopolitics and less prepared for future outbreaks. David culver, CNN Beijing.