The research, which hasn't been peer-reviewed, is based on satellite imagery of traffic movements around hospitals in Wuhan and the tracking of online searches for specific medical symptoms. It says there was a noticeable rise in vehicles parking outside six hospitals in the city from late August to 1 December 2019. This coincided, says the Harvard report, with an increase in searches for possible coronavirus symptoms such as "cough" and "diarrhoea".
This would be an important finding because the earliest reported case in Wuhan wasn't until the beginning of December. The academics write: "While we cannot confirm if the increased volume was directly related to the new virus, our evidence supports other recent work showing that emergence happened before identification at the Huanan Seafood market." The Harvard study has gained a lot of traction in the media, with President Trump, who has been highly critical of China's pandemic response, tweeting a Fox News item highlighting the researchers' findings. The tweet has been viewed more than three million times.
The study claims there was an increase in online queries for coronavirus symptoms, particularly "diarrhoea", on popular Chinese search engine Baidu. However, Baidu company officials have disputed their findings, saying there was in fact a decrease in searches for "diarrhoea" over this period. So, what's going on?