techniques may make genetically modified viruses indistinguishable from natural viruses, according to academic journal articles. For instance, a 2017 dissertation by a WIV student showed that reverse genetic cloning techniques—which are standard techniques used in advanced molecular laboratories—left no trace of genetic modification of SARS-like coronaviruses. · It will be difficult to increase our confidence that the distinguishing features in SARS-CoV-2 emerged naturally without a better understanding of the diversity of coronaviruses in nature and how often recombination occurs during co-infection of multiple coronaviruses within a particular host. For example, academic literature has indicated that a FCS had previously been inserted into SARS-CoV-1, the causative agent of SARS, complicating differentiation of how such a feature may have appeared. [ 5 ] · The WIV previously created chimeras, or combinations, of SARS-like coronaviruses, but this information does not provide insight into whether SARS-CoV-2 was genetically engineered by the WIV. No IC analysts assess that SARS-CoV-2 was the result of laboratory adaptation, although some analysts do not have enough information to make this determination. Repeated passage of a closely related virus through animals or cell culture—which we consider laboratory adaptation and not genetic engineering—could result in some features of SARS-CoV-2, according to publicly available information. However, it probably would take years of laboratory adaptation using the appropriate cell types and a virus that is more closely related to SARSCoV-2 than ones currently known to generate the number of mutations separating SARS-CoV-2 from any known coronavirus strains, judging from scientific journal articles. Such processes would require differentiation and maintenance of primary cells and the development of appropriate animal models. [ 6 ] China’s Lack of Foreknowledge of SARS-CoV-2 The IC assesses China’s officials probably did not have foreknowledge that SARS-CoV-2 existed before WIV researchers isolated it after public recognition of the virus in the general population. Accordingly, if the pandemic originated from a laboratory-associated incident, they probably were unaware in the initial months that such an incident had occurred. · Early in the pandemic, the WIV identified that a new virus was responsible for the outbreak in Wuhan. It is therefore assessed that WIV researchers pivoted to COVID-19-related work to address the outbreak and characterize the virus. These activities suggest that WIV personnel were unaware of the existence of SARS-CoV-2 until the outbreak was underway. Two Plausible Hypotheses of Pandemic Origin IC analysts assess that a natural origin and a laboratoryassociated incident are both plausible hypotheses for how SARS-CoV-2 first infected humans. Analysts, however, disagree on which is more likely, or whether an assessment can be made at all, given the lack of diagnosticity of the available information. Most agencies are unable to make higher than low confidence assessments for these reasons, and confidence levels are tempered by plausible arguments for the opposing hypothesis. For these hypotheses, IC analysts consider an exposure that occurs during animal sampling activity that supports biological research to be a laboratoryassociated incident and not natural contact. What follows is a look at the cases that can be made for these competing hypotheses. The Case for the Natural Origin Hypothesis Some IC analysts assess with low confidence that the first human COVID-19 infection most likely was caused by natural exposure to an animal that carried SARSCoV-2 or a close progenitor virus—a virus that would likely be more than 99 percent similar to SARS-CoV-2. Four IC elements, the National Intelligence Council, and some analysts at elements that are unable to coalesce around either explanation are among this group. Analysts at these agencies give weight to China’s officials' lack of foreknowledge and highlight the precedent of past novel infectious disease outbreaks having zoonotic origins, the wide diversity of animals that are susceptible to SARS-CoV-2 infection, and the range of scenarios—to include animal trafficking, farming, sale, and rescue—in China that enable zoonotic transmission. Although no confirmed animal source of SARS-CoV-2 has been identified, to include a reservoir or intermediate species, analysts that assess the pandemic was due to natural causes note that in many previous zoonotic outbreaks, the identification of animal sources has taken years, and in some cases, animal sources have not been identified. · These analysts assess that WIV’s activities in early 2020 related to SARS-CoV-2 are a strong indicator that the WIV lacked foreknowledge of the virus. · They also see the potential that a laboratory worker inadvertently was infected while collecting unknown animal specimens to be less likely than an infection occurring through numerous hunters, farmers, merchants, and others who have frequent, natural contact with animals. · Given China’s poor public health infrastructure and the potential for asymptomatic infection, some analysts that lean towards a natural origin argue that China’s infectious disease surveillance system would not have been able to detect the SARS-CoV-2 exposure as quickly as a suspected exposure in