Since the start of the COVID-19 pandemic, scientists, governments, and others have worked to find the origin of the SARS-CoV-2 virus. Like other outbreaks, the virus came from a virus found in bats. It likely spread to humans through another animal in nature or during live wildlife trade, such as in food markets. Some people have suggested the virus might have been accidentally released from a laboratory, but these ideas are not supported by evidence. False stories about the virus's origin have spread widely.
Researchers are still studying whether SARS-CoV-2 came directly from bats or through another animal, such as pangolins, civets, or raccoon dogs. Genetic evidence suggests the virus jumped from animals to humans around late 2019. Similar to the SARS-CoV-1 outbreak between 2002 and 2004, efforts to find the origin of SARS-CoV-2 have taken many years. The World Health Organization and other scientists have investigated the virus's origin since 2020. However, as of 2025, no clear answer has been found about its exact geographic or animal origin.
In 2025, the World Health Organization and an independent review concluded that the virus most likely came from animals, not a laboratory. They said more information, such as early patient records, details about wildlife trade, and records from labs in Wuhan, is needed to fully understand the origin.
In 2026, a study by virologist Joel Wertheim and colleagues at UCSD compared how viruses like Ebola and influenza change over time. They found that SARS-CoV-2's changes matched those of five natural outbreaks but did not match the 1977 Russian flu, which likely came from a lab. Wertheim and other WHO experts believe the virus likely came from bats and spread to animals sold in the Wuhan market.
Zoonosis
Scientists have studied how SARS-CoV-2, the virus that causes COVID-19, first appeared in humans. Most evidence suggests that horseshoe bats are the most likely original source of the virus. The viruses most closely related to SARS-CoV-2, called BANAL-52 and RaTG13, were found in bat droppings in Laos and China. These viruses are estimated to have diverged from SARS-CoV-2 about 50 years ago (between 38 and 72 years).
Bats are known to carry many types of coronaviruses. Studies show that humans have antibodies to these viruses, indicating that direct contact with bats may be common. The spread of SARS-CoV-2 to humans likely happened because of increased human activities that brought people closer to bat habitats. Factors like climate change, habitat destruction, and wildlife trade have also made it more likely for viruses to jump from animals to humans. A study supported by the European Union found that climate change may have influenced the spread of the virus by changing where bats live.
The first human cases of SARS-CoV-2 were reported in Wuhan, China, but the exact first case is still unknown. RaTG13 was found in bats in a mine in Yunnan Province, which is about 1,500 kilometers (930 miles) away from Wuhan. Few bat coronaviruses have been found in Hubei Province, where Wuhan is located.
Scientists also believe that SARS-CoV-2 may have spread to humans through an intermediate animal host. This would mean the virus first infected another animal before spreading to people. This pathway could allow the virus to adapt better to humans through an animal with proteins more similar to humans, though this is not required. The virus’s ability to infect other species, such as mink, supports this possibility.
In July 2022, two studies published in Science provided new genetic and epidemiological evidence suggesting the pandemic likely began at the Huanan Seafood Wholesale Market in Wuhan and did not originate in a laboratory.
A 2024 study of samples from the Huanan Seafood Wholesale Market found genetic material from possible intermediate hosts. Raccoon dogs were identified as the most likely candidates. The study also suggests these raccoon dogs may have come from southern China, where the closest known relatives of SARS-CoV-2 in bats were found.
Unlikely scenarios
Scientists agree that the virus causing COVID-19, called SARS-CoV-2, likely came from bats. However, the exact way this happened is not fully understood. Some ideas, such as the virus spreading through food products, are not considered likely.
A theory suggests the virus might have come from a laboratory. This idea is controversial because most scientists believe the virus spread naturally from animals to humans, not through human-made processes. Evidence shows that SARS-CoV-2 probably lived in bats first and then moved to humans through other animals, such as those sold at the Huanan Seafood Market in Wuhan, China, in late 2019. Scientists have not found any proof that the virus was created in a lab or that it existed in a lab before the pandemic.
Some people believe the virus leaked from the Wuhan Institute of Virology (WIV), but this idea is not supported by evidence. Many large cities have labs that study viruses, and outbreaks often begin in rural areas but are first noticed in cities. The WIV’s location near the outbreak area led to some suspicion, but scientists say this connection is not strong. Some claims about the lab, such as suggestions that the virus was engineered, are based on incorrect information.
The lab leak idea appeared early in the pandemic and was promoted by some people in the United States, causing tension between the U.S. and China. Scientists and media outlets mostly dismissed the theory as a conspiracy. In 2021, the World Health Organization (WHO) said the lab leak was "extremely unlikely," though they did not rule it out completely. China later refused to allow outside experts to check its labs.
Investigations
In January 2020, the Wuhan Municipal Health Commission in China began an investigation after hospitals reported cases of pneumonia with unknown causes. This led to the closure of the Huanan Seafood Wholesale Market on 1 January 2020 for cleaning and disinfecting. The Chinese Center for Disease Control and Prevention (CCDC) entered the market the same day to collect samples. However, because animals had already been removed before officials arrived, no animal samples were taken, which might have provided clearer information about the cause of the disease.
In April 2020, China limited the publication of academic research on the novel coronavirus. Any studies about the virus’s origin required approval from the Central Government. While this did not stop research or sharing of findings, especially with international scientists, some research was conducted under the guidance of the Chinese government. For example, Dr. Ian Lipkin, a U.S. scientist, worked with Chinese researchers through the CCDC to study the virus’s origin. His long-term collaboration with Chinese officials, including Premier Li Keqiang, helped facilitate this work.
The Huanan live-animal market was suspected as a possible source of the virus because many early cases of illness were linked to the area. In January 2021, a team of scientists from the World Health Organization (WHO) visited the market to investigate the origins of the virus. Based on the evidence available, the WHO concluded that the virus’s origin was still unknown. The Chinese government stated that the market was not the source and claimed the virus likely came from outside China. Until June 2021, Chinese officials denied that live animals were sold at the Huanan market.
In February 2022, some Chinese researchers shared an early analysis of swab samples from the Huanan market. They suggested the virus may have been introduced by humans, not animals. However, gaps in the analysis and the lack of raw data raised questions about the findings.
In March 2023, data from the swab samples was released or leaked online. A preliminary review by international scientists suggested that the virus may have originated from animals. While the data did not prove that raccoon dogs were the missing link in the virus’s transmission chain from bats to humans, it showed that these animals were present in the market during the outbreak. This strengthened the idea that the market was a possible origin.
Efforts to collaborate with Chinese researchers were not answered, and the raw data was later removed from the online database. In March 2023, an international group of scientists shared their findings with the WHO’s Scientific Advisory Group for Origins of Novel Pathogens, where Chinese researchers were also present. George Gao, the former head of the CCDC and lead author of the 2022 study, said the new data did not reveal anything new and refused to explain why the data was removed.
In March 2023, the WHO director-general criticized China for not sharing the data earlier and called for greater transparency. Additional data from other samples has not yet been made public. Maria Van Kerkhove, the WHO’s lead on COVID-19, urged China to release this information immediately.
In 2024, the Chinese Center for Disease Control and Prevention published a study on its surveillance of the Huanan Seafood Wholesale Market. The study found 74 positive environmental samples out of 923 tested, three successful virus isolations from market swabs, and no positive results in 457 animal samples collected after the market closed. The researchers concluded that the virus likely spread through contaminated environments caused by infected people. They shared raw data with both Chinese and international research groups.
In April 2025, the Chinese government released a white paper titled “Covid-19 Prevention, Control and Origins Tracing: China's Actions and Stance.” It stated that Wuhan was not the natural origin of the virus and described a laboratory incident as “extremely unlikely.” The document summarized Chinese research, including a 2019 blood-donor study that found no specific antibodies, wildlife screening that did not detect the virus, and investigations into the possibility of the virus entering China through cold-chain supply chains. It also called for further research outside China.
After a June 2025 review by the WHO’s Scientific Advisory Group, the National Health Commission in China criticized parts of the report, calling them “false information based on subjective speculation.” It reaffirmed the conclusions of the 2021 joint WHO-China study. As of June 2025, the WHO noted that investigations into the virus’s origin in Wuhan were still incomplete and that China had not shared several requested datasets, including early patient sequences, market supply-chain details, and biosafety records from Wuhan research facilities.
In February 2020, the U.S. Office of Science and Technology Policy asked the National Academies of Sciences, Engineering, and Medicine to gather experts to determine what data and samples are needed to understand the origins of the virus.
In April 2020, U.S. intelligence agencies investigated whether the virus originated from an accidental lab leak in China. However, by the end of April, U.S. intelligence concluded the virus was not man-made or genetically modified.
U.S. officials criticized the terms of the WHO’s initial investigation, which allowed Chinese scientists to lead the first phase of research. In January 2021, U.S. Secretary of State Mike Pompeo urged the WHO to address three issues: illnesses among researchers at the Wuhan Institute of Virology in 2019, the institute’s research on the “RaTG13” virus and “gain of function” experiments, and its connections to the Chinese military. The U.S. also called for the WHO to interview caregivers, former patients, and lab workers in Wuhan, which China opposed. Australia also supported these efforts.