Big Data Findings: The U.S. COVID-19 “patient zero” may have emerged as early as April 2019.

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A study based on big-data modeling and analysis, published on the 22nd by the Chinese Academy of Sciences’ preprint platform, indicates that the date when the probability of the first COVID‑19 case in the United States reached 50% most often falls between August and October 2019, with the earliest estimate being April 26, 2019, in Rhode Island.

Tracing the origins of a virus is crucial for the prevention and control of infectious diseases. A series of previous studies have shown that countries including the United States, Spain, France, Italy, and Brazil already exhibited evidence of viral infection well before the COVID‑19 outbreak in China.

The researchers wrote: “A series of previous studies have shown that, in countries including the United States, Spain, France, Italy, and Brazil, evidence of viral infection had already emerged well before the COVID‑19 outbreak in China.”

The study argues that combining mathematical modeling with artificial intelligence to conduct both qualitative and quantitative analyses of infectious diseases can reveal the underlying patterns of their spread. Drawing on epidemic transmission models and big‑data analytics, the researchers developed an optimization framework and, using publicly available data, estimated the origins of outbreaks in 12 states in the northeastern United States as well as in Wuhan and Zhejiang Province in China.

After analyzing daily COVID-19 case data released by local health authorities in 11 U.S. states and the District of Columbia, the researchers concluded that they estimate there is a 50% probability that the first U.S. case of COVID-19 emerged between August and October 2019—well before the nation’s first confirmed case on January 20, 2020.

The computational results indicate that the COVID-19 epidemic in the United States likely began to spread around September 2019.

Calculations indicate that the date on which the probability of the first case in Wuhan, China, reaching 50% was December 20, 2019, and in Zhejiang Province, China, it was December 23, 2019. Based on these findings, it is highly probable that the COVID‑19 epidemic in China had already begun to spread by late December 2019. This conclusion is broadly consistent with epidemiological investigation results, thereby validating the accuracy and reliability of this computational approach.

(This article is reprinted from China Daily.)