Coronavirus may have been in Wuhan in August, study suggests
Coronavirus
may have been present and spreading in Wuhan as early as August last year,
according to a study that analysed satellite imagery of car parks outside major
hospitals and search engine data.
The
study, by researchers from Harvard Medical School, Boston University of Public
Health and Boston children’s hospital, looked at images captured between
January 2018 and April 2020 and found a “steep increase” in vehicle counts
starting in August 2019 and peaking in December 2019. Between September and
October, five of the six hospitals observed had their highest daily volume of
cars in the period analysed.
China’s
foreign ministry rejected the study, calling it “extremely absurd”.
According
to the study, the increase in vehicle volume coincided with a rise in queries
on the Chinese search engine Baidu for “cough” and “diarrhoea”, about three
weeks before the confirmed rise in coronavirus cases in early 2020. The
researchers noted that while queries for cough coincided with the influenza
season, diarrhoea is a symptom specific to Covid-19.
“Increased
hospital traffic and symptom search data in Wuhan preceded the documented start
of the Sars-CoV-2 pandemic in December 2019,” the researchers said in a
preprint, published by Harvard’s DASH repository.
“In August, we identify a unique
increase in searches for diarrhoea which was neither seen in previous flu
seasons or mirrored in the cough search data,” it said.
China’s
foreign ministry spokeswoman Hua Chunying said on Tuesday in a regular press
briefing that she had not seen the study but she rejected its conclusions.
“I think it is absurd, actually
extremely absurd, to draw this kind of conclusion based on superficial
observations such as traffic volume,” she said.
The
origins of Covid-19, which was first detected in a cluster of cases associated
with the Huanan seafood market in late December, has become an increasingly
sensitive question as China fights off accusations that it should be blamed for
the pandemic, which has killed more than 400,000 people around the world.
The
authors of the study, which is still under peer review, acknowledged that they
could not confirm whether the increased vehicle volume was directly related to
the new virus. Wuhan would have been entering influenza season; several doctors
said that in December some schools had cancelled classes because of the flu.
Other
limitations include the presence of tall buildings, trees and smog, which
limited the number of high-resolution images that could be taken. There was
also limited archival footage of Wuhan in previous years because of a “lack of
commercial interest”.
