Satellite images of hospital parking lots in Wuhan suggest the coronavirus – which stemmed from the Chinese city – may have been spreading in China as early as last August.
A new study from Harvard Medical School, which is yet to be peer-reviewed, found a “dramatic increase in hospital traffic outside five major Wuhan hospitals beginning late summer and early fall 2019”, Harvard Medical professor and lead author of the research, Dr John Brownstein, said.
Dr Brownstein said the traffic increase also “coincided with” an uptick in searches on Chinese search engine Baidu for “certain symptoms that would later be determined as closely associated with the novel coronavirus”.
While the team have acknowledged the evidence is circumstantial, Dr Brownstein said the study makes for an important new data point in the mystery of COVID-19’s origins, with the disease only thought to have originated in November.
“Something was happening in October,” Dr Brownstein, also chief innovation officer at Boston’s Children’s Hospital and director of the medical centre’s Computational Epidemiology Lab, said.
“Clearly, there was some level of social disruption taking place well before what was previously identified as the start of the novel coronavirus pandemic.”
While individual hospitals had days of “high relative volume in both fall and winter 2019”, five of the six hospitals showed their “highest relative daily volume of the analysed series, coinciding with elevated levels of Baidu search queries for the terms ‘diarrhoea’ and ‘cough’,” the team, which included researchers from Boston University and Boston Children’s Hospital, wrote.
Dr Brownstein told CNN the study was all about “trying to piece together a complicated puzzle of what was taking place at the time”.
“The data is especially compelling because we saw increases in people searching for gastrointestinal disease – diarrhoea – which were increasing at a level that we hadn’t seen at all, historically, and we now know that gastrointestinal symptoms are a really important marker for COVID,” he said.
“A huge percentage of people that actually end up testing positive in Wuhan actually had presented symptoms of diarrhoea.”
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Dr Brownstein said the inspiration for the study was based on a previous one “years ago”, which showed hospitals in Latin America become exceedingly busy during flu season.
“You could predict flu season just by looking at the parking lots.”
While he said the team couldn’t confirm if the increased volume of cars in hospital parking lots in Wuhan was directly related to coronavirus, “our evidence supports other recent work showing that emergence happened before identification at the Huanan Seafood Market”.
While disease ecologist Peter Daszak told ABC the Harvard study is “absolutely fascinating”, chief science officer at the Centre for Discovery and Innovation in New Jersey, David Perlin, said he wasn’t entirely convinced.
“I think some of the methods are questionable and their interpretation is slightly over-interpreted,” he said.
“The problem is we only have a subset of data here. I always worry when people start drawing inferences from data subsets, cherrypicking data (like the internet searches). It’s suggestive.”
More than seven million people around the world have been infected with COVID-19, according to Johns Hopkins University, and more than 404,000 people have died.