New study suggests Covid-19 may have been circulating in Wuhan since August last year 1
A new study carried out by researchers from the Harvard Medical School, Boston University of Public Health and Boston children’s hospital used satellite imagery of parking lots and disease-related search engine queries to investigate the possibility that corona virus may have been circulating in Wuhan since August last year.
For the study, researchers collected over 111 satellite images of Wuhan from January 9, 2018 to April 30, 2020 resulting in 140 successful daily extractions of parking lot volume from hospitals. As per their analysis, between 2018 and 2020 there was a general upward trend of increased hospital occupancy and a “steep increase” in volume starting August 2019. Further, while individual hospitals have days of high relative volume in both Fall and Winter 2019, between September and October 2019, five of the six hospitals show their highest relative daily volume, which coincides with elevated search queries for the term “diarrhea” and “cough”.
So what does this mean?
Essentially, the researchers are saying that while it cannot be confirmed if the increase in the volume of hospital traffic and symptom search data in Wuhan was directly related to the coronavirus, they say that there is some evidence to believe that the disease might have been spreading before its identification at the Huanan seafood market.
“In August, we identify a unique increase in searches for diarrhea which was neither seen in previous flu seasons or mirrored in the cough search data. While surprising, this finding lines up with the recent recognition that gastrointestinal (GI) symptoms are a unique feature of COVID19 disease and may be the chief complaint of a significant proportion of presenting patients,” the study says. The authors have cited a study carried out by the Wuhan Union Hospital and Wuhan Tongji Medical University, which says that while respiratory symptoms are common indicators of COVID-19, a “potentially large” segment of patients with digestive symptoms, such as diarrhea play an important role in community transmission.
It is also possible that the initial rise in GI symptoms may have been ignored as an early signal of COVID-19 since the surveillance systems were looking for a respiratory pathogen, that are generally associated with symptoms such as fever, sore throat and cough.