WHO team probing coronavirus origins identifies two 'most likely' scenarios
A team of World Health Organization (WHO) experts investigating the origin of the novel coronavirus SARS-CoV-2 in China has identified two "most likely" scenarios. The new virus had made headlines in December 2019 after small outbreaks were reported in China's Wuhan city. It has since spread around the world infecting 106 million people and killing over 2.3 million. Here are more details.
- Intermediary host species scenario most likely: WHO expert
- Earlier studies suggested SARS-CoV-2 reached humans through bats
- Another possibility: Transmission through frozen products
- Cold chain transmission scenario would require further studies
- Transmission through lab-related incident 'extremely unlikely'
Intermediary host species scenario most likely: WHO expert
Addressing a press conference on Tuesday, WHO expert Peter Ben Embarek said a team probing four hypotheses around the transmission of the virus to humans has narrowed down two most likely scenarios. One involves an intermediary host species, widely hypothesized since the early stages of the pandemic. Embarek said this is the most likely scenario through which the virus was transmitted to humans.
Earlier studies suggested SARS-CoV-2 reached humans through bats
Embarek said, "Our initial findings suggest that the introduction through an intermediary host species is the most likely pathway and one way that will require more studies and more specific targeted research." In the early stages of the pandemic, preliminary studies had suggested that bats could be the source of transmission to humans as coronaviruses present in bats are 95% identical to SARS-CoV-2.
Another possibility: Transmission through frozen products
Embarek said there is also the possibility of transmission through the trade of frozen products. The virus can survive in frozen environments, but the possibility of cold chain transmission of coronaviruses needs further investigation, the WHO's food safety scientist said. This hypothesis has often been pushed by China, which has repeatedly announced findings of coronavirus traces on imported food packaging.
Cold chain transmission scenario would require further studies
During the press briefing, Embarek stressed that investigation into the cold chain transmission scenario would require a study to investigate whether a frozen wild animal in a market setting could spread the virus under the right conditions.
Transmission through lab-related incident 'extremely unlikely'
The WHO expert also said that a direct transmission from an animal reservoir to a human, also known as "direct zoonotic spillover," is also likely. He said this hypothesis is generating "recommendations for future studies." He added that the possibility of a laboratory-related incident is "extremely unlikely" to explain the introduction of the virus to the human population.
