According to a research paper published by the Harvard Medical School, the Coronavirus outbreak in China may have begun in late summer or early fall of 2019, much before it was reported to the world in December last year. The paper titled, “Analysis of hospital traffic and search engine data in Wuhan China indicates early disease activity in the Fall of 2019” was jointly written by Benjamin Rader, Nsoesie, Elaine Okanyene, Yiyao L. Barnoon, Lauren Goodwin, and John S. Brownstein.
The study observed a dramatic increase in hospital traffic and Baidu search queries related to symptoms of Coronavirus in late summer and early Fall of 2019 and thus preceding the documented start of COVID-19 pandemic in December. As per the epidemiological studies conducted earlier, 2/3 rd of the Coronavirus cases in Wuhan were found to have links with the Huanan wet markets.
The Harvard paper observed that Coronavirus may have been transmitting in Wuhan even before the identification of the wet market as a possible cause of spread. The study observed that the deadly pathogen may have adapted itself for ‘human transmission’ by the time it was reported in December 2019.
Methodology of the Harvard Research Paper
Earlier used in Latin America, the scientists used high-resolution satellite images (with an average resolution of 70 cm) from RS metrics to determine ‘hospital occupancy’ in Wuhan. The study identified 6 hospitals, namely Hubei Women and Children’s, Wuhan Tianyou, Wuhan Central, Wuhan Tongji Medical University, Wuhan Union, and Zhongnan Hospital of Wuhan University for analysis.
The research paper further estimated the time and date of each image, besides the address, latitude and longitude of each hospital. The dataset was then compared against a baseline for both weekdays and weekends at the hospitals. As for the search queries, the scientists checked daily data of web and mobile search logs between April 2017 and May 2020. Besides, data was also collected for influenza-like diseases from the Children’s Hospital of Wuhan and Wuhan No. 1 Hospital.
Results and Analysis
While there was a general upward trend in hospital traffic between 2018 and 2020, the study observed an increase in hospital occupancy from August 2019 with the traffic reaching its peak in December. As per the study, 5 of the 6 hospitals showed their highest relative daily volume between September and October last year.
Diarrhea and cough which are common symptoms of Coronavirus coincide with Baidu search results during the said period. Interestingly, the search query and hospital traffic also reduced after a lockdown was imposed in Wuhan on January 23. The study also noted an increase in hospital volume in the spring of this year, besides increased search queries for cough and diarrhea in May 2020.
Heavy hospital traffic can be observed in October 2019 which reduced drastically by February 2020, post lockdown. An increase in the number of vehicles (marked in red) in parking lots can also be noted between October 2018 and October 2019 at Wuhan Tianyou hospital.
While the study could not directly confirm that the dramatic increase in hospital traffic, it gave credence to the hypothesis that the outbreak of the pandemic may have happened before its identification in the wet markets of Wuhan. The unique increase in search queries for a Coronavirus symptom such as diarrhoea was not seen in preceding influenza seasons which further corroborates the hypothesis.