The leader of international experts investigating the origins of COVID-19 in China says they saw no evidence of large outbreaks of the disease prior to its December 2019 discovery in the city of Wuhan.
Peter Ben Embarek, an expert in viral illnesses for the World Health Organization, said Tuesday in Wuhan that his team’s findings indicate COVID-19 probably originated in bats, but says it is unlikely the bats were in Wuhan.
The team visited the city’s Huanan Seafood Market, which was initially believed to be the epicenter of the outbreak, the Wuhan Institute of Virology and laboratories at state facilities, including the Wuhan Center for Disease Control.
Embarek said at a news conference the theory that the virus leaked from a laboratory is extremely unlikely, and that his team will not investigate it further.
Embarek said the most likely pathway for the virus was a crossover into humans from an intermediary species, which he said “could have been very convoluted.” He also said the idea that COVID-19 can be transmitted through trade in frozen products is possible.
Dr. Liang Wannian, an expert with China’s Health Commission, told reporters at the briefing the novel coronavirus could have been circulating in other regions before it was officially identified in Wuhan.
The WHO dispatched Embarek and his 10-member team to Wuhan last month to track down the source of the virus, which has killed more than 2.3 million people among more than 106 million infected worldwide.
Monday the WHO expressed concern about new reports that vaccines against the coronavirus may not sufficiently protect against new variants.
On Sunday, South Africa suspended its vaccination campaign against COVID-19 after a new study revealed that the AstraZeneca vaccine it was using is less effective against a variant of the virus found in the country.
WHO Director-General Tedros Adhanom Ghebreyesus said Monday at a media briefing that the decision is “a reminder that we need to do everything we can to reduce circulation of the virus with proven public health measures.”
The study, conducted by the University of the Witwatersrand in Johannesburg and not yet peer reviewed, concluded that the British vaccine offered only "limited protection against moderate forms of the disease caused by the South African variant, in young adults."
The news was a blow to South Africa, which has seen more than 46,000 people die from the virus. It had planned to begin inoculating its population with a million doses of the AstraZeneca vaccine in the coming days. But the study found that the vaccine was only 22% effective in moderate cases of the South African variant of the disease.
The study did not explore the vaccine’s effect against severe cases. The variant has been found in at least 32 other countries, including the United States.
AstraZeneca said Sunday it was developing another vaccine that would be more effective against the South African variant, which could be expected by this autumn.
But WHO’s chief scientist, Dr. Soumya Swaminathan, cautioned Monday that countries should not assume the AstraZeneca vaccine does not work, noting that all available evidence shows that vaccines reduce death, hospitalizations and severe disease.