145-589: The COVID-19 lab leak theory , or lab leak hypothesis , is the idea that SARS-CoV-2 , the virus that caused the COVID-19 pandemic , came from a laboratory. This claim is highly controversial; most scientists believe the virus spilled into human populations through natural zoonosis (transfer directly from an infected non-human animal), similar to the SARS-CoV-1 and MERS-CoV outbreaks, and consistent with other pandemics in human history . Available evidence suggests that
290-451: A common ancestor . An ancestor of SARS-CoV-2 likely acquired "generalist" binding to several different species through adaptive evolution in bats and an intermediate host species. Estimates based on genomic sequences and contact tracing have placed the origin point of SARS-CoV-2 in humans as between mid-October and mid-November 2019. Some scientists (such as Fauci above and CIRAD 's Roger Frutos) have suggested slow, undetected circulation in
435-469: A human virus [such as SARS-CoV2] can transmit among mink , there's no basis to assume a bat virus [also SARS-CoV2] can't transmit among humans. Us humans may think we're very special – but to a virus we are just another mammalian host." The WHO-convened Global Study of Origins of SARS-CoV-2 , written by a joint team of Chinese and international scientists and published in March 2021, assessed introduction through
580-476: A natural reservoir has not been confirmed. The original source of viral transmission to humans remains unclear, as does whether the virus became pathogenic (capable of causing disease) before or after a spillover event. Bats, a large reservoir of betacoronaviruses , are considered the most likely natural reservoir of SARS‑CoV‑2. Differences between bat coronaviruses and SARS‑CoV‑2 suggest that humans may have been infected via an intermediate host . Research into
725-425: A public health emergency of international concern from January 30, 2020, to May 5, 2023. SARS‑CoV‑2 is a positive-sense single-stranded RNA virus that is contagious in humans. SARS‑CoV‑2 is a strain of the species Betacoronavirus pandemicum (SARSr-CoV), as is SARS-CoV-1 , the virus that caused the 2002–2004 SARS outbreak . There are animal-borne coronavirus strains more closely related to SARS-CoV-2,
870-498: A captive animal or its respiratory droplets or feces. Former CDC director Robert R. Redfield said in March 2021 that in his opinion the most likely cause of the virus was a laboratory escape, which "doesn't imply any intentionality", and that as a virologist, he did not believe it made "biological sense" for the virus to be so "efficient in human to human transmission" from the early outbreak. The fact that scientists have not been successful in finding an intermediate host that picked up
1015-638: A component of the original funding proposal. Importantly, the NIH spokesman said this finding was provided in a late progress report, and was not available before prior statements about experiments at the WIV. An August 2021 interim report authored by the minority staff of the Republican members of the US House Foreign Affairs Committee said that a laboratory leak origin for SARS-CoV-2 was more likely than
1160-552: A concern. In July 2022, two papers published in Science described novel epidemiological and genetic evidence that suggested the pandemic likely began at the Huanan Seafood Wholesale Market and did not come from a laboratory. The principal hypothesis for the origin of SARS-CoV-2 is that it became infectious to humans through a natural spillover event (zoonosis). That it became infectious to humans through escape from
1305-467: A family of viruses. By 12 January 2020, five genomes of SARS‑CoV‑2 had been isolated from Wuhan and reported by the Chinese Center for Disease Control and Prevention (CCDC) and other institutions; the number of genomes increased to 42 by 30 January 2020. A phylogenetic analysis of those samples showed they were "highly related with at most seven mutations relative to a common ancestor ", implying that
1450-424: A helical nucleocapsid . Six structural proteins are generated: N (nucleocapsid), P ( phosphoprotein ), M (matrix), F (fusion), G (glycoprotein) and L (RNA polymerase). The P open reading frame also encodes three nonstructural proteins, C, V and W. There are two envelope glycoproteins. The G glycoprotein ectodomain assembles as a homotetramer to form the viral anti-receptor or attachment protein, which binds to
1595-437: A kind of conjunction fallacy . The Wuhan Institute of Virology (WIV) had been conducting research on SARS-like bat coronaviruses since 2005, and was involved in 2015 experiments that some experts (such as Richard Ebright ) have characterized as gain-of-function . Others (including Ralph Baric ) have disputed the characterization, pointing out that the experiments in question (involving chimeric viruses ) were not conducted at
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#17330862885531740-546: A lab leak are characteristic of conspiracy theories . Central to many is the misplaced suspicion about the proximity of the outbreak to a virology institute that studies coronaviruses , the Wuhan Institute of Virology (WIV). Most large Chinese cities have laboratories that study coronaviruses, and virus outbreaks typically begin in rural areas, but are first noticed in large cities. If a coronavirus outbreak occurs in China, there
1885-533: A lab leak origin for SARS-CoV-2. Such assessments are not equivalent to scientific activity, but weigh the veracity of sources as the basis for making an intelligence report. An August 2021 report made at the request of President Biden assessed that the Chinese government did not have foreknowledge of the COVID-19 outbreak. Overall, the report was not conclusive about the virus' origin. Of eight assembled teams , four (and
2030-403: A lab-acquired infection leading to an epidemic is the 1977 Russian flu which was probably caused by a leaked strain of H1N1 that had circulated naturally until the 1950s. Previous novel disease outbreaks, such as AIDS , H1N1/09 , SARS , and Ebola have been the subject of conspiracy theories and allegations that the causative agent was created in or escaped from a laboratory. Each of these
2175-399: A laboratory incident to be "extremely unlikely" and not supported by any available evidence, although the report stated that this possibility could not be wholly ruled out without further evidence. The report stated that human spillover via an intermediate animal host was the most likely explanation, with direct spillover from bats next most likely. Introduction through the food supply chain and
2320-460: A laboratory leak. The SAGO chair said in a press conference that "the strongest evidence is still around a zoonotic transmission". The AP described the report as a "sharp reversal" of the WHO's previous assessment, and Science.org described reactions from academics as mixed. In early 2023, the WHO abandoned its original investigation into the origin of SARS-CoV-2, delegating work to its standing committee,
2465-433: A laboratory where it was being studied is a minority position. The available evidence supports zoonosis. Although the origin of SARS-CoV-2 is not definitively known, arguments used in support of a laboratory leak are characteristic of conspiratorial thinking. Most new infectious diseases begin with a spillover event from animals, and furthermore, they spill over spontaneously (either by contact with wildlife animals, which are
2610-597: A laboratory, and there was no evidence of any biosafety incident. Proponents of the lab leak hypothesis reacted by accusing the agencies of conspiring with the Chinese, or of being incompetent. Covering the story for the Sydney Morning Herald , its science reporter Liam Mannix wrote that the US report marked the end of the lab leak case, and that it had ended "not with a bang, but a whimper". SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 ( SARS‑CoV‑2 )
2755-678: A membrane protein that regulates the renin–angiotensin system. During the initial outbreak in Wuhan , China, various names were used for the virus; some names used by different sources included "the coronavirus" or "Wuhan coronavirus". In January 2020, the World Health Organization (WHO) recommended "2019 novel coronavirus" (2019-nCoV) as the provisional name for the virus. This was in accordance with WHO's 2015 guidance against using geographical locations, animal species, or groups of people in disease and virus names. On 11 February 2020,
2900-413: A mink euthanasia campaign rendering it virtually extinct. Each SARS-CoV-2 virion is 60–140 nanometres (2.4 × 10 –5.5 × 10 in) in diameter; its mass within the global human populace has been estimated as being between 0.1 and 10 kilograms. Like other coronaviruses, SARS-CoV-2 has four structural proteins, known as the S ( spike ), E ( envelope ), M ( membrane ), and N ( nucleocapsid ) proteins;
3045-459: A nationwide campaign to educate people on the dangers of Japanese encephalitis and its vector, Culex mosquitoes. Symptoms of infection from the Malaysian outbreak were primarily encephalitic in humans and respiratory in pigs. Later outbreaks have caused respiratory illness in humans, increasing the likelihood of human-to-human transmission and indicating the existence of more dangerous strains of
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#17330862885533190-534: A natural one. The report alleged that SARS-CoV-2 emerged in humans as a result of gain-of-function research made on the RaTG13 virus, collected in a cave in Yunnan province in 2012, which was afterwards accidentally released some time before 12 September 2019, when the database of the Wuhan Institute of Virology went offline. The August 2021 report relies mostly on existing public evidence, combined with internal documents from
3335-518: A nefarious coverup to the Chinese government". The use of xenophobic rhetoric also caused a rise in anti-Chinese sentiment. On social media the idea that COVID was a Chinese biological weapon has become widespread, and accords with rhetoric about how a yellow peril threatens white people. Science historian Fred Cooper and colleagues write that in the United Kingdom, attitudes to the Chinese have long been tainted by xenophobic stereotypes. Cooper draws
3480-548: A parallel between the Wuhan lab leak narrative, and the machinations of fictional supervillain Fu Manchu , who is "expert in the deadly application of animal and biological agents" and who has been depicted on television shows as threatening the West with lethal diseases. In the early days of the COVID-19 pandemic, speculation about a laboratory leak was confined to conspiracy-minded portions of
3625-407: A potential leak requires "further investigation, potentially with additional missions involving specialist experts". He proposed a second phase of WHO investigation, which he said should take a closer look at the lab leak idea, and asked the Chinese government to be "transparent" and release relevant data. Later on 17 July, Tedros called for "audits of relevant laboratories and research institutions" in
3770-421: A range of animals—such as cats, ferrets, hamsters, non-human primates, minks, tree shrews, raccoon dogs, fruit bats, and rabbits—that are susceptible and permissive to SARS-CoV-2 infection. Some institutions have advised that those infected with SARS‑CoV‑2 restrict their contact with animals. On 1 February 2020, the World Health Organization (WHO) indicated that "transmission from asymptomatic cases
3915-539: A sample of viral RNA and named it RaBtCoV/4991. Later, Shi's group published a paper about a virus named RaTG13 in Nature in February 2020. Via sequence comparisons, it became clear that RaBtCoV/4991 and RaTG13 were likely the same virus. Shi has said that the renaming was done to reflect the origin location and year of the virus. Some proponents, including Nicholas Wade and pseudonymous DRASTIC member "TheSeeker268", argued that
4060-822: A sample size large enough to reliably estimate vaccine effectiveness with sufficient statistical power is difficult. Nipah virus infection outbreaks have been reported in Malaysia, Singapore, Bangladesh and India. The highest mortality due to Nipah virus infection has occurred in Bangladesh, where outbreaks are typically seen in winter. Nipah virus first appeared in 1998, in peninsular Malaysia in pigs and pig farmers. By mid-1999, more than 265 human cases of encephalitis, including 105 deaths, had been reported in Malaysia, and 11 cases of either encephalitis or respiratory illness with one fatality were reported in Singapore. In 2001, Nipah virus
4205-488: A scenario, while being a lab leak, would also fit our first hypothesis of direct transmission of the virus from bat to human." The United States, European Union, and 13 other countries criticized the WHO-convened study, calling for transparency from the Chinese government and access to the raw data and original samples. Chinese officials described these criticisms as "an attempt to politicise the study". Scientists involved in
4350-550: A significant source of income for farmers, the Nipah virus outbreak in Malaysia originated from pigs and their enclosures. The extensive culling of pigs due to the outbreak resulted in increased poverty and challenges related to recovery in the affected regions. Limited public awareness about safe eating practices and the dangers linked to wildlife can increase exposure risks. Public health campaigns focused on food safety and avoiding bat habitats are essential for lowering these risks. In
4495-430: A single linear RNA segment. Coronaviruses infect humans, other mammals, including livestock and companion animals, and avian species. Human coronaviruses are capable of causing illnesses ranging from the common cold to more severe diseases such as Middle East respiratory syndrome (MERS, fatality rate ~34%). SARS-CoV-2 is the seventh known coronavirus to infect people, after 229E , NL63 , OC43 , HKU1 , MERS-CoV , and
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4640-412: A site. The furin cleavage site PRRAR↓ is highly similar to that of the feline coronavirus , an alphacoronavirus 1 strain. Viral genetic sequence data can provide critical information about whether viruses separated by time and space are likely to be epidemiologically linked. With a sufficient number of sequenced genomes , it is possible to reconstruct a phylogenetic tree of the mutation history of
4785-562: A smaller number of humans before a threshold event (such as replication in a larger number of hosts in a larger city like Wuhan) could explain an undetected adaption period. The first known human infections from SARS‑CoV‑2 were discovered in Wuhan, China, in December 2019. Because many of the early infectees were workers at the Huanan Seafood Market , it was originally suggested that the virus might have originated from wild animals sold in
4930-536: A total of 11 cases (ten confirmed, one probable) resulting in 8 deaths, a case fatality rate of 73%. This outbreak resulted in the highest number of cases reported since 2015 in Bangladesh, and ten of the 11 cases during the 2023 outbreak had a confirmed history of consuming date palm sap. In July 2024, an outbreak was confirmed in Kerala state in India. A 14-year-old boy died and an additional 60 people were identified as being in
5075-655: A wide geographic distribution of the viruses. No infection of humans or other species have been observed in Cambodia, Thailand or Africa as of May 2018. In September 2023, India reported at least five infections and two deaths. In July 2024 a new infection occurred and a 14-year-old boy died as a result of it. These symptoms can be followed by more serious conditions including: The first cases of Nipah virus infection were identified in 1998, when an outbreak of neurological and respiratory disease on pig farms in peninsular Malaysia caused 265 human cases, with 108 deaths. The virus
5220-453: Is a high likelihood it will occur near a large city, and therefore near a laboratory studying coronaviruses. The idea of a leak at the WIV also gained support due to secrecy during the Chinese government's response . The lab leak theory and its weaponization by politicians have both leveraged and increased anti-Chinese racism . Scientists from WIV had previously collected virus samples from bats in
5365-420: Is a prime target for vaccine development as well as antibody therapy. One head-specific antibody, m102.4, has been used in compassionate use cases and has completed Phase 1 clinical trials. The F glycoprotein forms a trimer , which mediates membrane fusion. Ephrins B2 and B3 have been identified as the main receptors for Nipah virus. Ephrin sub-types have a complex distribution of expression throughout
5510-404: Is a strain of coronavirus that causes COVID-19 , the respiratory illness responsible for the COVID-19 pandemic . The virus previously had the provisional name 2019 novel coronavirus ( 2019-nCoV ), and has also been called human coronavirus 2019 ( HCoV-19 or hCoV-19 ). First identified in the city of Wuhan , Hubei, China, the World Health Organization designated the outbreak
5655-445: Is also present (and even more frequent) in other coronaviruses, including MERS-CoV , and that a codon being rare does not mean it cannot be present naturally. If the CGG codon had been engineered into the virus, it should have mutated out of the virus as it circulated in humans in the wild over several years, but the opposite has occurred. In fact, the presence of the furin cleavage site, which
5800-477: Is another possible cause of infection. Preliminary research indicates that the virus may remain viable on plastic ( polypropylene ) and stainless steel ( AISI 304 ) for up to three days, but it does not survive on cardboard for more than one day or on copper for more than four hours. The virus is inactivated by soap, which destabilizes its lipid bilayer . Viral RNA has also been found in stool samples and semen from infected individuals. The degree to which
5945-492: Is another potential treatment option for Nipah virus. Favipiravir and fusion inhibitory peptides may also show potential; however, additional studies are required to evaluate their effectiveness. In January 2024 a candidate vaccine, ChAdOx1 NipahB, commenced Phase I clinical trials after completing laboratory and animal testing. However, the low occurrence of Nipah virus presents a significant challenge for conducting traditional phase 3 vaccine efficacy trials, as achieving
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6090-425: Is approximately 30,000 bases in length, relatively long for a coronavirus—which in turn carry the largest genomes among all RNA families. Its genome consists nearly entirely of protein-coding sequences, a trait shared with other coronaviruses. A distinguishing feature of SARS‑CoV‑2 is its incorporation of a polybasic site cleaved by furin , which appears to be an important element enhancing its virulence. It
6235-522: Is disputed among experts. According to emailed statements by Shi Zhengli , director of the Center for Emerging Infectious Diseases at the Wuhan Institute of Virology, her lab has not conducted any unpublished gain-of-function experiments on coronaviruses, and all WIV staff and students tested negative for the virus in the early days of the pandemic. One strand of argumentation in favor of a lab leak rests on
6380-401: Is likely not a major driver of transmission". One meta-analysis found that 17% of infections are asymptomatic, and asymptomatic individuals were 42% less likely to transmit the virus. However, an epidemiological model of the beginning of the outbreak in China suggested that "pre-symptomatic shedding may be typical among documented infections" and that subclinical infections may have been
6525-680: Is likely to have occurred in late 2019. Epidemiological studies estimate that in the period between December 2019 and September 2020 each infection resulted in an average of 2.4–3.4 new infections when no members of the community were immune and no preventive measures were taken. However, some subsequent variants have become more infectious. The virus is airborne and primarily spreads between people through close contact and via aerosols and respiratory droplets that are exhaled when talking, breathing, or otherwise exhaling, as well as those produced from coughs and sneezes. It enters human cells by binding to angiotensin-converting enzyme 2 (ACE2),
6670-518: Is most probably the result of recombination , and is further unsurprising since the genetic lineage of these viruses has not been adequately explored, sampled, or sequenced. A common occurrence among other coronaviruses (including MERS-CoV, HCoV-OC43 , HCoV-HKU1 , and appearing in near-identical fashion in HKU9-1 ), the site is preceded by short palindromic sequences suggestive of natural recombination caused by simple evolutionary mechanisms. Additionally,
6815-481: Is no evidence that any laboratory had samples of SARS-CoV-2, or a plausible ancestor virus, prior to the start of the COVID-19 pandemic. Various sources have hypothesised that SARS-CoV-2 could have leaked from the Wuhan Institute of Virology or another laboratory in Wuhan, such as the Wuhan Center for Disease Control . The theories vary on whether this was an intentional act or an accident. Theories also vary on whether
6960-495: Is not a single discrete proposed scenario, but a collection of various proposed scenarios on a spectrum with, at one end, a careless accident from legitimate research; at the other, the engineering and release of a Chinese biological weapon . While the proposed scenarios are theoretically subject to evidence-based investigation, it is not clear that any can be sufficiently falsified to placate lab leak supporters, and they are fed by pseudoscientific and conspiratorial thinking. There
7105-429: Is now understood to have a natural origin. Anti-biotechnology activists falsely claimed that a plant pathogen of olive trees was the result of scientists' work, despite evidence to the contrary that the pathogen was not a laboratory strain. Studies later showed the origin was long before the workshop that was the subject of the false claims, and a more typical route of introduction by an imported plant. The lab leak theory
7250-399: Is responsible for a significant increase in transmissibility, largely outweighs any disadvantageous immune responses from B-cells triggered by the genetic sequences which code for it. Another source of speculation is the mere presence of the furin cleavage site. It is absent in the closest known relatives of SARS-CoV-2 (but present in other betacoronaviruses , e.g. BtHpCoV-ZJ13). This anomaly
7395-467: Is subject to, and that it is improbable that research on hard-to-obtain coronaviruses could occur under the radar. Kentucky Senator Rand Paul alleged that the US National Institutes of Health (NIH) had been funding gain-of-function research in Wuhan, accusing researchers including epidemiologist Ralph Baric of creating "super-viruses". Both Fauci and NIH Director Francis Collins denied that
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#17330862885537540-449: Is the cost and inconvenience of high-containment facilities. Australian virologist Danielle Anderson, who was the last foreign scientist to visit the WIV before the pandemic, said the lab "worked in the same way as any other high-containment lab". She also said it had "strict safety protocols". The Huanan Seafood Market may have only served as a jumping off point for a virus that was already circulating in Wuhan, facilitating rapid expansion of
7685-420: Is the least common arginine codon in human pathogenic betacoronaviruses. Partially, this lack of CGG codons in human pathogenic coronaviruses is due to natural selection ; B-cells in the human body recognize areas on virus genomes where C and G are next to each other (so-called CpG islands ). The CGG codon makes up 5% of the arginine codons in the SARS-CoV-1 genome, and it makes up 3% of the arginine codons in
7830-606: Is the protein responsible for allowing the virus to attach to and fuse with the membrane of a host cell; specifically, its S1 subunit catalyzes attachment, the S2 subunit fusion. Nipah virus Nipah virus is a bat-borne, zoonotic virus that causes Nipah virus infection in humans and other animals, a disease with a very high mortality rate (40-75%). Numerous disease outbreaks caused by Nipah virus have occurred in South East Africa and Southeast Asia. Nipah virus belongs to
7975-410: Is thought to be due to an increasing overlap between bat habitats and piggeries in peninsular Malaysia. In one outbreak, fruit orchards were in close proximity to the piggery, allowing the spillage of urine, faeces and partially eaten fruit onto the pigs. Retrospective studies demonstrate that viral spillover into pigs may have been occurring, undetected, in Malaysia since 1996. During 1998, viral spread
8120-484: The CCP from before and during the early days of the pandemic. The interim report was published coinciding with a joint investigation from ProPublica and Vanity Fair . Immediately following its publication, the report was heavily criticized by experts in diplomacy and the Chinese language for mistranslations and misinterpretations of Chinese documents. Bacteriologist and lab leak theory proponent Richard Ebright criticized
8265-417: The Huanan Seafood Market was considered less likely. A small group of researchers said that they would not trust the report's conclusions because it was overseen by the Chinese government, and some observers felt the WHO's statement was premature. Other scientists found the report convincing, and said there was no evidence of a laboratory origin for the virus. WHO Director-General Tedros Adhanom stated that
8410-610: The International Committee on Taxonomy of Viruses adopted the official name "severe acute respiratory syndrome coronavirus 2" (SARS‑CoV‑2). To avoid confusion with the disease SARS , the WHO sometimes refers to SARS‑CoV‑2 as "the COVID-19 virus" in public health communications and the name HCoV-19 was included in some research articles. Referring to COVID-19 as the "Wuhan virus" has been described as dangerous by WHO officials, and as xenophobic by many journalists and academics. Human-to-human transmission of SARS‑CoV‑2
8555-702: The National Intelligence Council ) were inclined, with low confidence, to uphold a zoonotic origin, three were unable to reach a conclusion and one (the FBI ) supported, with moderate confidence, a lab leak. British intelligence agencies believe it is "feasible" that the virus began with a leak from a Chinese laboratory. In February 2023, The Wall Street Journal reported that the United States Department of Energy , based on new intelligence, had shifted its view from "undecided" to "low confidence" that
8700-459: The SARS-CoV-2 genome. Proponents of an engineered virus, including journalist Nicholas Wade , say that two such uncommon codons in a row are evidence for a laboratory experiment; because of the low chance of a CGG codon pair occurring in nature, and in contrast, the common usage of CGG codons for arginine in genetic engineering work. This has been debunked by scientists, who note that the CGG codon
8845-571: The Scientific Advisory Group for Origins of Novel Pathogens (SAGO). This work will attempt to establish a COVID-19 timeline, search for similar viruses, and conduct further laboratory studies on animals and human samples. Members of DRASTIC, a collection of internet activists advocating for the lab leak theory, have raised concerns over a respiratory outbreak that happened in the spring of 2012 near an abandoned copper mine in China, which Shi Zhengli's group investigated. Shi's group collected
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#17330862885538990-469: The index case ". The authors later published a correction that showed that shedding began earlier than first estimated, four to five days before symptoms appear. There is uncertainty about reinfection and long-term immunity. It is not known how common reinfection is, but reports have indicated that it is occurring with variable severity. The first reported case of reinfection was a 33-year-old man from Hong Kong who first tested positive on 26 March 2020,
9135-483: The nasal cavity is seemingly the dominant initial site of infection, with subsequent aspiration -mediated virus-seeding into the lungs in SARS‑CoV‑2 pathogenesis. They found that there was an infection gradient from high in proximal towards low in distal pulmonary epithelial cultures, with a focal infection in ciliated cells and type 2 pneumocytes in the airway and alveolar regions respectively. Studies have identified
9280-574: The 1998–99 Nipah virus outbreak in Malaysia, 140 patients received ribavirin, with their outcomes assessed against 54 historical controls who either lacked access to the drug or declined treatment. Results indicated a reduced mortality rate (32% compared to 54%) among those treated, although the use of historical controls could have introduced bias. No further clinical studies with ribavirin have been conducted, and research in animal models has not demonstrated its effectiveness against Nipah or Hendra virus infections. Studies in animal models have also explored
9425-531: The Chinese had a secret vaccine standing by for use. Some proposed that the Chinese government and World Health Organization were operating together in a conspiracy. The American president of the time, Donald Trump, used anti-Chinese rhetoric (such as "Kung flu") to feed the idea, and said in an April 2020 news conference that he had documents supporting the idea that SARS-CoV-2 had come from the Wuhan Institute of Virology. In reaction to this politicized environment, most mainstream science and media sources assumed that
9570-492: The N protein holds the RNA genome, and the S, E, and M proteins together create the viral envelope . Coronavirus S proteins are glycoproteins and also type I membrane proteins (membranes containing a single transmembrane domain oriented on the extracellular side). They are divided into two functional parts (S1 and S2). In SARS-CoV-2, the spike protein, which has been imaged at the atomic level using cryogenic electron microscopy ,
9715-538: The Philippines, and Thailand, is also recognized as a potential risk factor for future Nipah virus outbreaks. Global travel and trade increase the risk of Nipah virus spreading beyond its endemic regions, as undetected cases could cross borders undetected. This calls for strong international surveillance and rapid response systems to monitor and contain potential outbreaks effectively. The clinical impact of Nipah virus highlights ongoing global public health risks due to
9860-544: The SARS-CoV-2 virus was originally harbored by bats , and spread to humans from infected wild animals, functioning as an intermediate host , at the Huanan Seafood Market in Wuhan , Hubei, China, in December 2019. Several candidate animal species have been identified as potential intermediate hosts. There is no evidence SARS-CoV-2 existed in any laboratory prior to the pandemic, or that any suspicious biosecurity incidents happened in any laboratory. Many scenarios proposed for
10005-401: The SARS‑CoV‑2 genome (matches above 90 percent may sound high, but in genomic terms it is a wide evolutionary gap ). In addition, despite similarities in a few critical amino acids, pangolin virus samples exhibit poor binding to the human ACE2 receptor. SARS‑CoV‑2 belongs to the broad family of viruses known as coronaviruses . It is a positive-sense single-stranded RNA (+ssRNA) virus, with
10150-409: The US government supported such research. Baric likewise rejected Paul's allegations, saying his lab's research into cross-species transmission of bat coronaviruses did not qualify as gain-of-function. While a 2017 study of chimeric bat coronaviruses at the WIV listed NIH as a sponsor, NIH funding was only related to sample collection. A Washington Post fact-checker commented that " EcoHealth funding
10295-468: The United States through promotion by conservative personalities in early 2020, fomenting tensions between the U.S. and China. Scientists and media outlets widely dismissed it as a conspiracy theory . The accidental leak idea had a resurgence in 2021. In March, the World Health Organization (WHO) published a report which deemed the possibility "extremely unlikely", though the WHO's director-general said
10440-661: The WHO Research and Development Blueprint. In cases of severe respiratory and neurological complications resulting from Nipah virus infection, healthcare professionals advise intensive supportive care as the primary treatment approach. In 2019, the World Health Organization (WHO) released an advanced draft of a research and development roadmap aimed at accelerating the creation of medical countermeasures, including diagnostics, treatments, and vaccines, to support effective and timely responses to Nipah virus outbreaks. In
10585-429: The WHO report, including Liang Wannian, John Watson, and Peter Daszak, objected to the criticism, and said that the report was an example of the collaboration and dialogue required to successfully continue investigations into the matter. On 15 July 2021, WHO Director-General Tedros Adhanom Ghebreyesus said that the COVID-19 lab leak theory had been prematurely discarded by the WHO, following his earlier statements that
10730-408: The WIV, but at UNC Chapel Hill , whose institutional biosafety committee assessed the experiments as not "gain-of-function". Baric did acknowledge the risks involved in such studies, writing, "Scientific review panels may deem similar studies building chimeric viruses based on circulating strains too risky to pursue ... The potential to prepare for and mitigate future outbreaks must be weighed against
10875-577: The amino acid sequence P RR A . This sequence is upstream of an arginine and serine which forms the S1/S2 cleavage site ( P RR A R ↓ S ) of the spike protein. Although such sites are a common naturally-occurring feature of other viruses within the Subfamily Orthocoronavirinae, it appears in few other viruses from the Beta-CoV genus, and it is unique among members of its subgenus for such
11020-417: The area of the initial COVID-19 cases. China's government refused saying it showed "disrespect" and "arrogance towards science". The United States criticised China's position on the follow-up origin probe as "irresponsible" and "dangerous". In June 2022, the WHO's Scientific Advisory Group for Origins of Novel Pathogens (SAGO) published a preliminary report urged a deeper investigation into the possibility of
11165-765: The body, where the B3 is noted to have particularly high expression in some forebrain sub-regions. Nipah virus has been isolated from Lyle's flying fox ( Pteropus lylei ) in Cambodia and viral RNA found in urine and saliva from P. lylei and Horsfield's roundleaf bat ( Hipposideros larvatus ) in Thailand. Ineffective forms of the virus has also been isolated from environmental samples of bat urine and partially eaten fruit in Malaysia. Antibodies to henipaviruses have also been found in fruit bats in Madagascar ( Pteropus rufus , Eidolon dupreanum ) and Ghana ( Eidolon helvum ) indicating
11310-555: The closest known sequence to SARS-CoV-2 until the discovery of BANAL-52 in horseshoe bats in Laos, but it is not its direct ancestor . Other closely related sequences were also identified in samples from local bat populations in Yunnan province. One such virus, RpYN06 , shares 97% identity with SARS-CoV-2 in one large part of its genome, but 94% identity overall. Such "chunks" of very highly identical nucleic acids are often implicated as evidence of
11455-418: The differences between what was then called 2019-nCoV and the virus from the 2003 SARS outbreak were insufficient to make them separate viral species . Therefore, they identified 2019-nCoV as a virus of Severe acute respiratory syndrome–related coronavirus . In July 2020, scientists reported that a more infectious SARS‑CoV‑2 variant with spike protein variant G614 has replaced D614 as the dominant form in
11600-723: The factors that lead to outbreaks and conducting studies to understand how the virus spreads between species can help create better prevention strategies and reduce the chances of future outbreaks. A major future challenge is to develop and maintain a supply of reliable, targeted, and affordable testing tools to enable rapid diagnostics in labs located in regions where the virus is likely to be found in wildlife reservoirs. Active collaboration between institutions and coordination among human and animal virologists are crucial for early outbreak detection and prompt implementation of preventive measures. The presence of fruit bats in various tropical countries, including Cambodia, Indonesia, Madagascar,
11745-640: The first human infection occurred in November or December 2019. Examination of the topology of the phylogenetic tree at the start of the pandemic also found high similarities between human isolates. As of 21 August 2021, 3,422 SARS‑CoV‑2 genomes, belonging to 19 strains, sampled on all continents except Antarctica were publicly available. On 11 February 2020, the International Committee on Taxonomy of Viruses announced that according to existing rules that compute hierarchical relationships among coronaviruses based on five conserved sequences of nucleic acids,
11890-495: The first infection, but the mechanisms that could account for this are not known. No natural reservoir for SARS-CoV-2 has been identified. Prior to the emergence of SARS-CoV-2 as a pathogen infecting humans, there had been two previous zoonosis -based coronavirus epidemics, those caused by SARS-CoV-1 and MERS-CoV . The first known infections from SARS‑CoV‑2 were discovered in Wuhan, China. The original source of viral transmission to humans remains unclear, as does whether
12035-458: The genus Henipavirus along with the Hendra virus , which has also caused disease outbreaks. Like other henipaviruses , the Nipah virus genome is a single (non-segmented) negative-sense, single-stranded RNA of over 18 kb, which is substantially longer than that of other paramyxoviruses . The enveloped virus particles are variable in shape, and can be filamentous or spherical; they contain
12180-434: The heads, resulting in a 2-up/2-down configuration where two heads are positioned distal to the virus and two heads are proximal. Due to the folding patterns and subsequent arrangement of the heads, only one of the four heads is positioned with its binding site accessible to associate with the host B2/B3 receptor. The G protein head domain is also highly antigenic, inducing head-specific antibodies in primate models. As such, it
12325-519: The high-risk category of having the disease. The Nipah virus (NiV) has been detected in several of the world's most densely populated areas, particularly in Southeast Asia (SEAR). This region covers just 5% of the Earth's total land area, yet it is home to 26% of the global population. Bangladesh is home to the world's most densely populated urban area, while Kerala, a state in southern India, ranks among
12470-523: The internet, including 4Chan and Infowars , but the ideas began to get wider traction after accusations about a "Chinese bioweapon" were originally published by Great Game India and then republished by the Red State Watch and Zero Hedge web sites. From there, the idea gained media traction and was championed by American conservative political figures. The idea split into variants, including one that proposed Asian people were immune to COVID, or that
12615-484: The key factor in the NiV outbreak in Malaysia during 1998–1999, as it increased human contact with bats infected with the virus. Widespread deforestation and habitat fragmentation drive wildlife, especially fruit bats, the natural reservoirs of the Nipah virus, into closer proximity with human communities and livestock. As bats lose their natural habitats, they increasingly venture into agricultural areas to find food, which raises
12760-406: The lab leak idea was no more than racially-fuelled propaganda, and by the summer of 2020 the idea was largely dismissed, until the next American president, Joe Biden, ordered an investigation into COVID's origins in 2021. Some have hypothesised the virus arose in humans from an accidental infection of laboratory workers by contact with a sample extracted from a wild animal or by direct contact with
12905-457: The lab leak theory typically omit to mention that most large Chinese cities have coronavirus research laboratories. Virus outbreaks tend to begin in rural areas, but are first noticed in large cities. Stephan Lewandowsky and colleagues write that the location of the Institute near the outbreak site is "literally a coincidence" and using that coincidence as a priori evidence for a lab leak typifies
13050-404: The lack of effective treatments and vaccines. A strong international focus on developing vaccines and treatments is essential to reduce the health effects and future risks of Nipah virus. Presently, there are no dedicated drugs or vaccines available for the treatment or prevention of Nipah virus infection. The World Health Organization (WHO) has designated Nipah virus as a priority disease within
13195-695: The likelihood of spillover events. Severe climatic changes have also been implicated in triggering NiV outbreaks in Bangladesh and India. The northwestern areas of Bangladesh have experienced extreme temperatures along with a rise in drought occurrences. The Nipah virus outbreak in Malaysia occurred following a drought linked to El Niño conditions. The particular weather patterns and changes have been associated with spillover events. In addition to droughts, flooding and rising sea levels have driven bats to migrate further into village areas. Climate change, and extreme weather events negatively impact biodiversity, animal distribution, and microflora, all of which may raise
13340-460: The likelihood of zoonotic agents emerging and infectious disease outbreaks occurring. The economic conditions, poverty levels, and population dynamics significantly influence a nation's overall strength; in areas where healthcare infrastructure is lacking, effectively managing outbreaks and delivering sufficient care to those infected becomes particularly difficult, worsening the consequences of Nipah virus outbreaks. While pig farming has served as
13485-555: The majority of cases, or with farmed animals). For example, the emergence of Nipah virus in Perak, Malaysia, and the 2002 outbreak of SARS-CoV-1 in Guangdong province, China, were natural zoonosis traced back to wildlife origin. COVID-19 is considered by scientists to be "of probable animal origin". It has been classified as a zoonotic disease (naturally transmissible from animals to humans). Some scientists dispute this classification, since
13630-423: The market, including civet cats, raccoon dogs, bats, or pangolins. Subsequent environmental analyses demonstrated the presence of SARS-CoV-2 in the market, with highest prevalence in areas of the market where animals known to be susceptible to SARS-CoV-2 infection were held. Early human cases clustered around the market, and included infections from two separate SARS-CoV-2 lineages. These two lineages demonstrated that
13775-415: The market. The Wuhan Institute of Virology and the Wuhan Center for Disease Control are located within miles of the original focal point of the pandemic, Wuhan's Huanan Seafood Wholesale Market, and this very closeness has made it easy for conspiracy theories to take root suggesting the laboratory must be the virus' origin. However virology labs are often built near potential outbreak areas. Proponents of
13920-471: The mine, in which Shi says that the virus was collected there, but that it was very likely not the cause of the miners' illnesses. According to the addendum, laboratory tests conducted on the workers' serum were negative, and "no antibodies to a SARS-like coronavirus had been found." One conspiracy theory spread in support a laboratory origin suggests SARS-CoV-2 was developed for gain-of-function research on coronaviruses. The exact meaning of "gain of function"
14065-491: The most closely known relative being the BANAL-52 bat coronavirus. SARS-CoV-2 is of zoonotic origin; its close genetic similarity to bat coronaviruses suggests it emerged from such a bat-borne virus . Research is ongoing as to whether SARS‑CoV‑2 came directly from bats or indirectly through any intermediate hosts. The virus shows little genetic diversity , indicating that the spillover event introducing SARS‑CoV‑2 to humans
14210-492: The most densely populated states in India. High population density leads to increased interactions among people and between humans and their environments, which, coupled with the presence of farm animals in densely populated areas, raises the risk of virus spillover. Deforestation in the Southeast Asia region is occurring at an alarming pace, driven by factors such as grazing, agricultural expansion, industrialization, and urban development. Deforestation has been identified as
14355-612: The much larger clades . Several different clade nomenclatures have been proposed. Nextstrain divides the variants into five clades (19A, 19B, 20A, 20B, and 20C), while GISAID divides them into seven (L, O, V, S, G, GH, and GR). Several notable variants of SARS-CoV-2 emerged in late 2020. The World Health Organization has currently declared five variants of concern , which are as follows: Other notable variants include 6 other WHO-designated variants under investigation and Cluster 5 , which emerged among mink in Denmark and resulted in
14500-563: The natural reservoir of the virus that caused the 2002–2004 SARS outbreak has resulted in the discovery of many SARS-like bat coronaviruses , most originating in horseshoe bats . The closest match by far, published in Nature (journal) in February 2022, were viruses BANAL-52 (96.8% resemblance to SARS‑CoV‑2), BANAL-103 and BANAL-236, collected in three different species of bats in Feuang , Laos. An earlier source published in February 2020 identified
14645-401: The natural reservoir of the virus that caused the 2002 SARS outbreak has resulted in the discovery of many SARS-like coronaviruses circulating in bats, most found in horseshoe bats . Analysis indicates that a virus collected from Rhinolophus affinis in a cave near the town of Tongguan in Yunnan province , designated RaTG13 , has a 96% resemblance to SARS‑CoV‑2. The RaTG13 virus genome was
14790-403: The negative consequences of such events on the reputation of a host institution and low risk for widespread epidemics. Epidemiologist Marc Lipsitch and bacteriologist Richard Ebright have said that the risk of laboratory-acquired infection (especially with modified pathogens ) is greater than widely believed. No epidemic has ever been caused by the leak of a novel virus. The only incident of
14935-524: The original SARS-CoV . Like the SARS-related coronavirus implicated in the 2003 SARS outbreak, SARS‑CoV‑2 is a member of the subgenus Sarbecovirus ( beta-CoV lineage B). Coronaviruses undergo frequent recombination. The mechanism of recombination in unsegmented RNA viruses such as SARS-CoV-2 is generally by copy-choice replication, in which gene material switches from one RNA template molecule to another during replication. The SARS-CoV-2 RNA sequence
15080-516: The outbreak. Laboratory leak incidents have occurred in the past. A Soviet research facility in 1979 leaked anthrax and at least 68 people died. The 2007 foot-and-mouth outbreak in the UK was caused by a leaky pipe at a high-security laboratory. The SARS virus escaped at least once, and probably twice, from a high-level biocontainment laboratory in China. Benign exposures to pathogens (which do not result in an infection) are probably under-reported, given
15225-474: The pandemic originated with a lab leak. In the intelligence community, "low confidence" means the information is sourced to low-quality or otherwise untrustworthy sources. In the wake of these reports, FBI Director Christopher Wray reiterated the bureau's assessment, saying that the Government of China was doing its best to thwart any investigation. White House National Security Advisor Jake Sullivan responded to
15370-1807: The pandemic. Coronavirus genomes and subgenomes encode six open reading frames (ORFs). In October 2020, researchers discovered a possible overlapping gene named ORF3d , in the SARS‑CoV‑2 genome . It is unknown if the protein produced by ORF3d has any function, but it provokes a strong immune response. ORF3d has been identified before, in a variant of coronavirus that infects pangolins . A phylogenetic tree based on whole-genome sequences of SARS-CoV-2 and related coronaviruses is: ( Bat ) Rc-o319 , 81% to SARS-CoV-2, Rhinolophus cornutus , Iwate , Japan Bat SL-ZXC21 , 88% to SARS-CoV-2, Rhinolophus pusillus , Zhoushan , Zhejiang Bat SL-ZC45 , 88% to SARS-CoV-2, Rhinolophus pusillus , Zhoushan, Zhejiang Pangolin SARSr-CoV-GX, 85.3% to SARS-CoV-2, Manis javanica , smuggled from Southeast Asia Pangolin SARSr-CoV-GD, 90.1% to SARS-CoV-2, Manis javanica , smuggled from Southeast Asia Bat RshSTT182, 92.6% to SARS-CoV-2, Rhinolophus shameli , Steung Treng , Cambodia Bat RshSTT200, 92.6% to SARS-CoV-2, Rhinolophus shameli , Steung Treng, Cambodia (Bat) RacCS203 , 91.5% to SARS-CoV-2, Rhinolophus acuminatus , Chachoengsao , Thailand (Bat) RmYN02 , 93.3% to SARS-CoV-2, Rhinolophus malayanus , Mengla , Yunnan (Bat) RpYN06 , 94.4% to SARS-CoV-2, Rhinolophus pusillus , Xishuangbanna , Yunnan (Bat) RaTG13 , 96.1% to SARS-CoV-2, Rhinolophus affinis , Mojiang , Yunnan (Bat) BANAL-52 , 96.8% to SARS-CoV-2, Rhinolophus malayanus , Vientiane , Laos SARS-CoV-2 SARS-CoV-1 , 79% to SARS-CoV-2 There are many thousands of variants of SARS-CoV-2, which can be grouped into
15515-440: The premise that there is something "unnatural" about the genetic makeup of the SARS-CoV-2 virus, showing it must have been created by genetic engineering. Some claims of bioengineering focus on the presence of two sequential cytosine - guanine -guanine (CGG) codons in the virus' RNA , more precisely in the crucial furin cleavage site. The CGG codon is one of several codons that translates into an arginine amino acid , and it
15660-453: The process more difficult, and that words are often twisted to become "fodder for conspiracy theories". The idea of an experiment conducted in 2015 on SARS-like coronaviruses being the source of the pandemic was reported in British tabloids early in the pandemic. Virologist Angela Rasmussen writes that this is unlikely, due to the intense scrutiny and government oversight gain-of-function research
15805-542: The receptor on the host cell. Each strand in the ectodomain consists of four distinct regions: at the N-terminal and connecting to the viral surface is the helical stalk, followed by the beta-sandwich neck domain, the linker region and finally, at the C-terminal, four heads which contain host cell receptor binding domains. Each head consists of a beta-propeller structure with six blades. There are three unique folding patterns of
15950-411: The renaming was an attempt to obscure the origins of the virus and hide how it could be related to a laboratory origin of the related SARS-CoV-2 virus. Scientists have said that RaTG-13 is too distantly related to be connected to the pandemic's origins, and could not be altered in a laboratory to create SARS-CoV-2. Nature later published an addendum to the 2020 RaTG13 paper addressing any possible link to
16095-413: The report as "an embarrassingly bad use of taxpayer money and resources." The final version of the report was released on 18 April 2023. The final version reiterated the interim position that the pandemic began in a laboratory incident in the fall of 2019, based on what it called a "preponderance of circumstantial evidence". In the United States, several intelligence agencies have assessed the likelihood of
16240-509: The report for packaging pre-existing and previously examined evidence as new information. Evolutionary biologist Michael Worobey commented that the document seemed to be either "a cynical effort to try to win Republican votes" in the November 2022 midterm elections, or "a bunch of staffers with no ability to understand the science who stumbled across a bunch of misinformation and disinformation-filled tweets." Virologist Angela Rasmussen described
16385-549: The report saying "some elements of the intelligence community have reached conclusions on one side, some on the other. A number of them have said they just don't have enough information to be sure", and there was still "no definitive answer" to the pandemic origins' question. The reassessment renewed the political debate around the issue in the US. In June 2023, the Office of the Director of National Intelligence declassified their report on
16530-410: The report's conclusions were not definitive. Subsequent plans for laboratory audits were rejected by China. Most scientists remain skeptical of the possibility of a laboratory origin, citing a lack of any supporting evidence for a lab leak and the abundant evidence supporting zoonosis. Though some scientists agree a lab leak should be examined as part of ongoing investigations , politicization remains
16675-431: The risk of creating more dangerous pathogens." The fact that the lab is in Wuhan, the city where the pandemic's early outbreak took place, and the fact that the research at WIV was being conducted under the less stringent biosafety levels (BSL) 2 and 3, has led to speculation that SARS-CoV-2 could have escaped from the Wuhan lab. Richard Ebright said one reason that lower-containment BSL-2 laboratories are sometimes used
16820-570: The role of pangolins as an intermediate host was initially posited (a study published in July 2020 suggested that pangolins are an intermediate host of SARS‑CoV‑2-like coronaviruses ), subsequent studies have not substantiated their contribution to the spillover. Evidence against this hypothesis includes the fact that pangolin virus samples are too distant to SARS-CoV-2: isolates obtained from pangolins seized in Guangdong were only 92% identical in sequence to
16965-504: The source of a majority of infections. That may explain how out of 217 on board a cruise liner that docked at Montevideo , only 24 of 128 who tested positive for viral RNA showed symptoms. Similarly, a study of ninety-four patients hospitalized in January and February 2020 estimated patients began shedding virus two to three days before symptoms appear and that "a substantial proportion of transmission probably occurred before first symptoms in
17110-555: The source. For a virus recently acquired through a cross-species transmission, rapid evolution is expected. The mutation rate estimated from early cases of SARS-CoV-2 was of 6.54 × 10 per site per year. Coronaviruses in general have high genetic plasticity , but SARS-CoV-2's viral evolution is slowed by the RNA proofreading capability of its replication machinery. For comparison, the viral mutation rate in vivo of SARS-CoV-2 has been found to be lower than that of influenza. Research into
17255-503: The spike (S) protein (not the whole virus) which would be distributed to bats in the wild to reduce the chances of future human outbreaks. One proposed alteration was to modify bat coronaviruses to insert a cleavage site for the Furin protease at the S1/S2 junction of the spike (S) viral protein. There is no evidence that any genetic manipulation or reverse genetics (a technique required to make chimeric viruses) of SARS-related bat coronaviruses
17400-474: The suboptimal configuration and poor targeting of the cleavage site for humans or mice when compared with known examples (such as HCoV-OC43 or HCoV-HKU1), along with the complex and onerous molecular biology work this would have required, is inconsistent with what would be expected from an engineered virus. Project DEFUSE was a rejected DARPA grant application, that proposed to sample bat coronaviruses from various locations in China. The rejected proposal document
17545-405: The team had experienced difficulty accessing raw data on early COVID-19 cases and that the least likely hypothesis, a lab leak, required additional investigation because "further data and studies will be needed to reach more robust conclusions". The leader of the WHO investigatory team, Peter Ben Embarek , said "An employee of the lab gets infected while working in a bat cave collecting samples. Such
17690-441: The use of chloroquine, both independently and with ribavirin, but it has not demonstrated any therapeutic benefit. A potentially more effective method is the application of monoclonal antibodies (mAbs), which can help neutralize the Nipah virus through passive administration. Treatment with anti-Nipah virus monoclonal antibodies (mAbs) could be beneficial for early intervention and post-exposure prophylaxis in individuals exposed to
17835-493: The virus RaTG13 , collected in bats in Mojiang , Yunnan, China to be the closest to SARS‑CoV‑2, with 96.1% resemblance. None of the above are its direct ancestor. Bats are considered the most likely natural reservoir of SARS‑CoV‑2. Differences between the bat coronavirus and SARS‑CoV‑2 suggest that humans may have been infected via an intermediate host; although the source of introduction into humans remains unknown. Although
17980-478: The virus became pathogenic before or after the spillover event . Because many of the early infectees were workers at the Huanan Seafood Market , it has been suggested that the virus might have originated from the market. However, other research indicates that visitors may have introduced the virus to the market, which then facilitated rapid expansion of the infections. A March 2021 WHO-convened report stated that human spillover via an intermediate animal host
18125-419: The virus from bats and passed it to humans is seen by some as evidence that supports a lab leak, according to The Guardian . University of Utah virologist Stephen Goldstein has criticized the scientific basis of Redfield's comments, saying that since SARS-CoV-2's spike protein is very effective at jumping between hosts, one shouldn't be surprised that it transmits efficiently among humans. Goldstein said "If
18270-478: The virus is infectious during the incubation period is uncertain, but research has indicated that the pharynx reaches peak viral load approximately four days after infection or in the first week of symptoms and declines thereafter. The duration of SARS-CoV-2 RNA shedding is generally between 3 and 46 days after symptom onset. A study by a team of researchers from the University of North Carolina found that
18415-587: The virus may be airborne as well, with aerosols potentially being able to transmit the virus. During human-to-human transmission, between 200 and 800 infectious SARS‑CoV‑2 virions are thought to initiate a new infection. If confirmed, aerosol transmission has biosafety implications because a major concern associated with the risk of working with emerging viruses in the laboratory is the generation of aerosols from various laboratory activities which are not immediately recognizable and may affect other scientific personnel. Indirect contact via contaminated surfaces
18560-430: The virus was actively infecting a population of animals in the market, and that sustained contact between those animals and humans had allowed for multiple viral transmissions into humans. All early cases of COVID-19 were later shown to be localized to the market and its immediate vicinity. While other wild animals susceptible to SARS-CoV-2 infection are known to have been sold at Huanan, no bats or pangolins were sold at
18705-490: The virus was modified by human activity prior to being released. By January 2020 some lab leak proponents were promoting a narrative with conspiracist components; such narratives were often supported using "racist tropes that suggest that epidemiological, genetic, or other scientific data had been purposefully withheld or altered to obscure the origin of the virus". David Gorski refers to "the blatant anti-Chinese racism and xenophobia behind lab leak, whose proponents often ascribe
18850-400: The virus' origins, in compliance with an Act of Congress compelling it to do so. The report stated that while the lab leak theory could not be ruled out, the overall assessment of the National Intelligence Council and a majority of IC assets (with low confidence) was that the pandemic most likely began as a zoonotic event. No evidence was found that SARS-CoV-2 or a progenitor virus existed in
18995-422: The virus. Another case study described a 25-year-old man from Nevada who tested positive for SARS‑CoV‑2 on 18 April 2020 and on 5 June 2020 (separated by two negative tests). Since genomic analyses showed significant genetic differences between the SARS‑CoV‑2 variant sampled on those two dates, the case study authors determined this was a reinfection. The man's second infection was symptomatically more severe than
19140-537: The virus. During the 1999 outbreak of Nipah virus, which occurred among pig farmers, the majority of human infections stemmed from direct contact with sick pigs and the unprotected handling of secretions from the pigs. Based on seroprevalence data and virus isolations, the primary reservoir for Nipah virus was identified as pteropid fruit bats, including Pteropus vampyrus ( large flying fox ), and Pteropus hypomelanus ( small flying fox ), both found in Malaysia. The transmission of Nipah virus from flying foxes to pigs
19285-692: The virus. The m102.4 antibody has demonstrated protective effects against lethal Nipah virus challenges in animal studies and has been administered under compassionate use to those exposed to either Hendra or Nipah viruses. In 2016, a phase 1 clinical trial for m102.4 was conducted in Australia with 40 participants, demonstrating that the treatment was safe and well-tolerated, with no signs of an immunogenic response. Further research requirements for mAb therapy involve conducting clinical trials in endemic regions to evaluate its safety, tolerability, effectiveness, and pharmacokinetic properties in more detail. Remdesivir
19430-410: The wild, and allegations that they also performed undisclosed work on such viruses are central to some versions of the idea. Some versions, particularly those alleging genome engineering , are based on misinformation or misrepresentations of scientific evidence. The idea that the virus was released from a laboratory (accidentally or deliberately) appeared early in the pandemic. It gained popularity in
19575-554: Was aided by the transfer of infected pigs to other farms, where new outbreaks occurred. The Nipah virus has been classified by the Centers for Disease Control and Prevention as a Category C agent . Nipah virus is one of several viruses identified by WHO as a potential cause of future epidemics in a new plan developed after the Ebola epidemic for urgent research and development toward new diagnostic tests, vaccines and medicines. Identifying
19720-414: Was confirmed on 20 January 2020 during the COVID-19 pandemic . Transmission was initially assumed to occur primarily via respiratory droplets from coughs and sneezes within a range of about 1.8 metres (6 ft). Laser light scattering experiments suggest that speaking is an additional mode of transmission and a far-reaching one, indoors, with little air flow. Other studies have suggested that
19865-452: Was discharged on 15 April 2020 after two negative tests, and tested positive again on 15 August 2020 (142 days later), which was confirmed by whole-genome sequencing showing that the viral genomes between the episodes belong to different clades . The findings had the implications that herd immunity may not eliminate the virus if reinfection is not an uncommon occurrence and that vaccines may not be able to provide lifelong protection against
20010-406: Was ever carried out at the WIV. All available evidence points to the SARS-CoV-2 furin cleavage site being the result of natural evolution. The situation reignited a debate over gain-of-function research , although the intense political rhetoric surrounding the issue has threatened to sideline serious inquiry over policy in this domain. Researchers have said the politicization of the debate is making
20155-476: Was first isolated. The outbreak was originally mistaken for Japanese encephalitis , but physicians in the area noted that persons who had been vaccinated against Japanese encephalitis were not protected in the epidemic, and the number of cases among adults was unusual. Although these observations were recorded in the first month of the outbreak, the Ministry of Health failed to take them into account, and launched
20300-463: Was isolated the following year in 1999. This outbreak resulted in the culling of one million pigs. In Singapore, 11 cases, including one death, occurred in abattoir workers exposed to pigs imported from the affected Malaysian farms. The name "Nipah" refers to the place, Sungai Nipah (literally ' nipah river') in Port Dickson , Negeri Sembilan , the source of the human case from which Nipah virus
20445-491: Was not related to the experiments, but the collection of samples", and that "statements about Baric's research appear overblown". In October 2021, a spokesman for the NIH acknowledged that the EcoHealth Alliance had provided new data demonstrating that in a mouse experiment, a coronavirus had caused more weight loss than expected. This was described as an unexpected consequence of the research, and not its intended outcome or
20590-608: Was posted online by DRASTIC in September 2021. Co-investigators on the rejected proposal included the EcoHealth Alliance 's Peter Daszak , Ralph Baric from UNC , Linfa Wang from Duke–NUS Medical School in Singapore, and Shi Zhengli from the Wuhan Institute of Virology. The grantees proposed to evaluate the ability of bat viruses to infect human cells in the laboratory using chimeric coronaviruses which were mutated in different locations, and to create protein-based vaccines out of
20735-546: Was reported from Meherpur District , Bangladesh and Siliguri , India. The outbreak again appeared in 2003, 2004 and 2005 in Naogaon District , Manikganj District , Rajbari District , Faridpur District and Tangail District . In Bangladesh there were also outbreaks in subsequent years. In September 2021, Nipah virus resurfaced in Kerala , India claiming the life of a 12-year-old boy. An outbreak of Nipah virus occurred during January and February 2023 in Bangladesh with
20880-437: Was suggested that the acquisition of the furin-cleavage site in the SARS-CoV-2 S protein was essential for zoonotic transfer to humans. The furin protease recognizes the canonical peptide sequence R X[ R / K ] R ↓X where the cleavage site is indicated by a down arrow and X is any amino acid . In SARS-CoV-2 the recognition site is formed by the incorporated 12 codon nucleotide sequence CCT CGG CGG GCA which corresponds to
21025-525: Was the most likely explanation, with direct spillover from bats next most likely. Introduction through the food supply chain and the Huanan Seafood Market was considered another possible, but less likely, explanation. An analysis in November 2021, however, said that the earliest-known case had been misidentified and that the preponderance of early cases linked to the Huanan Market argued for it being
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