COVID-19, which is considered to be the greatest infectious disease outbreak since the 1918-19 influenza pandemic, originated from central China’s Wuhan in December 2019. There have been several theories regarding the origin of the virus including animal origins, frozen or refrigerated food and Wuhan lab. The WHO had constituted a team that collaborated with the Chinese health commission to study the origin of the virus. The basic factors that the team kept in mind during the investigation were epidemiology (how COVID-19 spread among people), molecular epidemiology (the genetic makeup of the virus and its spread), and the role of animals and the environment. Dominic Dwyer, who was the Australian representative on the international World Health Organization’s (WHO) investigation into the origins of the SARS-CoV-2 virus, has written about the findings of his team over the four weeks of WHO’s mission in China. Dwyer wrote the first-person account a few days after German scientist Dr Roland Wiesendanger published a paper saying that he was “99.9% certain that the coronavirus came from the (Wuhan) laboratory.” Dwyer touched upon some of the conspiracy theories regarding the origin of the virus.
The WHO team visited the now-closed Wuhan wet market which was considered to be the source of the virus in the early days. They found that some domesticated wildlife such as bamboo rats, civets and ferret badgers raised for food may be susceptible to SARS-CoV-2, but none of the animal products tested positive for SARS-CoV-2 after the market’s closure. “There’s also genetic evidence generated during the mission for a transmission cluster there. Viral sequences from several of the market cases were identical, suggesting a transmission cluster. However, there was some diversity in other viral sequences, implying other unknown or unsampled chains of transmission,” according to the study. The team concluded that the now-closed Wuhan market, where around 10,000 people would be visiting in a day when it was open, acted more like a spreading agent rather than the source of origin.
Cold chain hypothesis
There is a theory that the virus might have originated from elsewhere via the farming, catching, processing, transporting, refrigeration or freezing of food. Dwyer said that environmental sampling in the market showed viral surface contamination which may indicate the introduction of SARS-CoV-2 through infected people, or contaminated animal products and “cold chain” products. However, the investigation of “cold chain” products and virus survival at low temperatures is still underway.
Dwyer described the Wuhan Institute of Virology as an impressive research facility where blood samples of scientists are routinely taken and stored. They couldn’t find any evidence in the blood samples as well as the biosecurity audits. “We looked at the closest virus to SARS-CoV-2 they were working on — the virus RaTG13 — which had been detected in caves in southern China where some miners had died seven years previously. But all the scientists had was a genetic sequence for this virus. They hadn’t managed to grow it in culture. While viruses certainly do escape from laboratories, this is rare. So, we concluded it was extremely unlikely this had happened in Wuhan,” he wrote.
Dwyer concluded that irrespective of where the virus originated, people will feel the long-term physical and psychological effects of the virus all over the world for a very long time. He added that the study in China was just the first phase and they would continue to investigate the evidence of the virus in other regions of the world.