A new study from the Harvard Medical School suggested that the novel coronavirus might have been spreading in Wuhan, China, the epicenter of the pandemic, as early as August of last year.
This time, they based the results with the help of satellite images as well as internet search results.
Studying Satellite Images and Internet Searches
In a report by CNN, the researchers have found satellite images of Wuhan hospitals, capturing more cars parking in the lots around late summer to fall of 2019 compared to the same months of 2018.
They have also found that there is a surge of internet search results linked to COVID-19 on China's Baidu search engine around that time.
The team's paper hasn't yet been peer-reviewed at the time of writing and is posted on Harvard's DASH server.
The team, led by John Brownstein, the chief innovation officer of the Boston Children's Hospital, wrote in the paper that they have found "a steep increase in volume starting in August 2019 and culminating with a peak in December 2019."
Through the satellite images that were captured from October 2018, the team counted 171 cars parked in the parking lot of Tianyou Hospital, which is the biggest one in Wuhan.
Nevertheless, a year later, satellite data has shown a total of 285 cars parked near the same hospital, seeing an increase of 67%, while there is a 90% increase of traffic in various other Wuhan hospitals at the same time period.
Increase of People Searching for Symptoms Related to COVID-19
Besides the traffic in Wuhan hospitals, the team also acquired data from Baidu, the Chinese equivalent to the Google search engine.
Through the data they acquired, the team saw the search results of many Chinese people coincided with the symptoms associated with COVID-19.
"Individual hospitals have days of high relative volume in both fall and winter 2019. However, between September and October 2019, five of the six hospitals show their highest relative daily volume of the analyzed series, coinciding with elevated levels of Baidu search queries for the terms 'diarrhea' and 'cough,'" the team wrote.
The Importance of the Study
Brownstein explained the importance of their research to the news outlet, saying that it's all about "trying to piece together a complicated puzzle" that was happening at the time.
The team's research would also help answer the question of where the virus came from and how it has evolved since the first time it appeared.
The head researcher also believes that the data they acquired is compelling, especially as they have seen a massive surge of people searching for gastrointestinal problems like diarrhea that they haven't seen before.
This is important as gastrointestinal problems, especially diarrhea, is a marker of COVID-19.
Using "validated data streams" is not a new technique when it comes to respiratory disease surveillance.
According to Brownstein, they had used the technique before. They discovered that Latin American hospitals would become busy during flu season and that they were able to predict when it would start by looking at the hospitals' parking lots.
